diff --git a/definitions/grib1/grid_definition_1.def b/definitions/grib1/grid_definition_1.def
index 0dbce8698..14caa71a8 100644
--- a/definitions/grib1/grid_definition_1.def
+++ b/definitions/grib1/grid_definition_1.def
@@ -64,6 +64,8 @@ iterator mercator(numberOfPoints,missingValue,values,
           jPointsAreConsecutive,
           alternativeRowScanning);
 
+nearest mercator(values,radius,Nx,Ny);
+
 meta latLonValues latlonvalues(values);
 alias latitudeLongitudeValues=latLonValues;
 meta latitudes latitudes(values,0);
diff --git a/definitions/grib2/template.3.10.def b/definitions/grib2/template.3.10.def
index 1a2f2d57f..818c43c09 100644
--- a/definitions/grib2/template.3.10.def
+++ b/definitions/grib2/template.3.10.def
@@ -75,6 +75,8 @@ iterator mercator(numberOfPoints,missingValue,values,
           iScansNegatively, jScansPositively,
           jPointsAreConsecutive, alternativeRowScanning);
 
+nearest mercator(values,radius,Nx,Ny);
+
 meta latLonValues latlonvalues(values);
 alias latitudeLongitudeValues=latLonValues;
 meta latitudes latitudes(values,0);
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 7db38f5c4..682f92310 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -346,6 +346,7 @@ list( APPEND grib_api_srcs
     grib_nearest_class_latlon_reduced.c
     grib_nearest_class_sh.c
     grib_nearest_class_lambert_conformal.c
+    grib_nearest_class_mercator.c
     grib_nearest_class_polar_stereographic.c
     grib_iterator_class_polar_stereographic.c
     grib_iterator_class_lambert_azimuthal_equal_area.c
diff --git a/src/Makefile.am b/src/Makefile.am
index 6055f9f33..2008953f4 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -361,6 +361,7 @@ libeccodes_la_prototypes= \
 	grib_nearest_class_latlon_reduced.c \
 	grib_nearest_class_sh.c \
 	grib_nearest_class_lambert_conformal.c \
+   	grib_nearest_class_mercator.c \
 	grib_nearest_class_polar_stereographic.c \
 	grib_iterator_class_polar_stereographic.c \
 	grib_iterator_class_lambert_azimuthal_equal_area.c  \
diff --git a/src/grib_nearest.c b/src/grib_nearest.c
index 64d277436..ca482fb04 100644
--- a/src/grib_nearest.c
+++ b/src/grib_nearest.c
@@ -323,6 +323,11 @@ int grib_nearest_find_generic(
         return ret;
     nearest->values_count = nvalues;
 
+    if (grib_is_earth_oblate(h)) {
+        grib_context_log(h->context, GRIB_LOG_ERROR, "Nearest neighbour functionality only supported for spherical earth.");
+        return GRIB_NOT_IMPLEMENTED;
+    }
+
     if ((ret = grib_get_long_internal(h, radius_keyname, &iradius)) != GRIB_SUCCESS)
         return ret;
     if (grib_is_missing(h, radius_keyname, &ret)) {
diff --git a/src/grib_nearest_class.h b/src/grib_nearest_class.h
index 772129e18..5962393cb 100644
--- a/src/grib_nearest_class.h
+++ b/src/grib_nearest_class.h
@@ -2,6 +2,7 @@
 extern grib_nearest_class* grib_nearest_class_gen;
 extern grib_nearest_class* grib_nearest_class_lambert_conformal;
 extern grib_nearest_class* grib_nearest_class_latlon_reduced;
+extern grib_nearest_class* grib_nearest_class_mercator;
 extern grib_nearest_class* grib_nearest_class_polar_stereographic;
 extern grib_nearest_class* grib_nearest_class_reduced;
 extern grib_nearest_class* grib_nearest_class_regular;
diff --git a/src/grib_nearest_class_lambert_conformal.c b/src/grib_nearest_class_lambert_conformal.c
index 994782d92..539dfe73f 100644
--- a/src/grib_nearest_class_lambert_conformal.c
+++ b/src/grib_nearest_class_lambert_conformal.c
@@ -107,9 +107,9 @@ static int find(grib_nearest* nearest, grib_handle* h,
 {
     grib_nearest_lambert_conformal* self = (grib_nearest_lambert_conformal*)nearest;
     return grib_nearest_find_generic(
-        nearest, h, inlat, inlon, flags,
+        nearest, h, inlat, inlon, flags,  /* inputs */
 
-        self->values_key,
+        self->values_key,  /* outputs to set the 'self' object */
         self->radius,
         &(self->lats),
         &(self->lats_count),
@@ -119,7 +119,7 @@ static int find(grib_nearest* nearest, grib_handle* h,
         self->Ni,
         self->Nj,
 
-        outlats, outlons,
+        outlats, outlons,  /* outputs of the find function */
         values, distances, indexes, len);
 }
 
diff --git a/src/grib_nearest_class_mercator.c b/src/grib_nearest_class_mercator.c
index 11dfa7a3f..699a103fb 100644
--- a/src/grib_nearest_class_mercator.c
+++ b/src/grib_nearest_class_mercator.c
@@ -107,9 +107,9 @@ static int find(grib_nearest* nearest, grib_handle* h,
 {
     grib_nearest_mercator* self = (grib_nearest_mercator*)nearest;
     return grib_nearest_find_generic(
-        nearest, h, inlat, inlon, flags,
+        nearest, h, inlat, inlon, flags, /* inputs */
 
-        self->values_key,
+        self->values_key,  /* outputs to set the 'self' object */
         self->radius,
         &(self->lats),
         &(self->lats_count),
@@ -119,7 +119,7 @@ static int find(grib_nearest* nearest, grib_handle* h,
         self->Ni,
         self->Nj,
 
-        outlats, outlons,
+        outlats, outlons,  /* outputs of the find function */
         values, distances, indexes, len);
 }
 
diff --git a/src/grib_nearest_class_polar_stereographic.c b/src/grib_nearest_class_polar_stereographic.c
index 64bb558b2..95271c197 100644
--- a/src/grib_nearest_class_polar_stereographic.c
+++ b/src/grib_nearest_class_polar_stereographic.c
@@ -107,9 +107,9 @@ static int find(grib_nearest* nearest, grib_handle* h,
 {
     grib_nearest_polar_stereographic* self = (grib_nearest_polar_stereographic*)nearest;
     return grib_nearest_find_generic(
-        nearest, h, inlat, inlon, flags,
+        nearest, h, inlat, inlon, flags, /* inputs */
 
-        self->values_key,
+        self->values_key,   /* outputs to set the 'self' object */
         self->radius,
         &(self->lats),
         &(self->lats_count),
@@ -119,7 +119,7 @@ static int find(grib_nearest* nearest, grib_handle* h,
         self->Ni,
         self->Nj,
 
-        outlats, outlons,
+        outlats, outlons,  /* outputs of the find function */
         values, distances, indexes, len);
 }
 
diff --git a/src/grib_nearest_factory.h b/src/grib_nearest_factory.h
index 211969962..8ec5cfedf 100644
--- a/src/grib_nearest_factory.h
+++ b/src/grib_nearest_factory.h
@@ -2,6 +2,7 @@
 { "gen", &grib_nearest_class_gen, },
 { "lambert_conformal", &grib_nearest_class_lambert_conformal, },
 { "latlon_reduced", &grib_nearest_class_latlon_reduced, },
+{ "mercator", &grib_nearest_class_mercator, },
 { "polar_stereographic", &grib_nearest_class_polar_stereographic, },
 { "reduced", &grib_nearest_class_reduced, },
 { "regular", &grib_nearest_class_regular, },
diff --git a/tests/grib_mercator.sh b/tests/grib_mercator.sh
index 1fb3f44bd..0a74ec485 100755
--- a/tests/grib_mercator.sh
+++ b/tests/grib_mercator.sh
@@ -30,5 +30,9 @@ EOF
 
 ${tools_dir}/grib_filter $tempFilter $input
 
+# Nearest function
+${tools_dir}/grib_ls -l 19,-97,1 $input > $tempOut
+grep -q "Point chosen #1 index=618" $tempOut
+
 # Clean up
 rm -f $tempFilter $tempOut