diff --git a/python/plugins/processing/algs/gdal/merge.py b/python/plugins/processing/algs/gdal/merge.py
index df8b44d9ad2..ee615bb412d 100644
--- a/python/plugins/processing/algs/gdal/merge.py
+++ b/python/plugins/processing/algs/gdal/merge.py
@@ -48,6 +48,7 @@ class merge(GdalAlgorithm):
     PCT = 'PCT'
     SEPARATE = 'SEPARATE'
     OPTIONS = 'OPTIONS'
+    EXTRA = 'EXTRA'
     DATA_TYPE = 'DATA_TYPE'
     NODATA_INPUT = 'NODATA_INPUT'
     NODATA_OUTPUT = 'NODATA_OUTPUT'
@@ -95,6 +96,13 @@ class merge(GdalAlgorithm):
                 'class': 'processing.algs.gdal.ui.RasterOptionsWidget.RasterOptionsWidgetWrapper'}})
         self.addParameter(options_param)
 
+        extra_param = QgsProcessingParameterString(self.EXTRA,
+                                                   self.tr('Additional command-line parameters'),
+                                                   defaultValue=None,
+                                                   optional=True)
+        extra_param.setFlags(extra_param.flags() | QgsProcessingParameterDefinition.FlagAdvanced)
+        self.addParameter(extra_param)
+
         self.addParameter(QgsProcessingParameterEnum(self.DATA_TYPE,
                                                      self.tr('Output data type'),
                                                      self.TYPES,
@@ -153,6 +161,10 @@ class merge(GdalAlgorithm):
         if options:
             arguments.extend(GdalUtils.parseCreationOptions(options))
 
+        if self.EXTRA in parameters and parameters[self.EXTRA] not in (None, ''):
+            extra = self.parameterAsString(parameters, self.EXTRA, context)
+            arguments.append(extra)
+
         arguments.append('-o')
         arguments.append(out)
 
diff --git a/python/plugins/processing/tests/GdalAlgorithmsTest.py b/python/plugins/processing/tests/GdalAlgorithmsTest.py
index 82bd09c884d..0685463b77a 100644
--- a/python/plugins/processing/tests/GdalAlgorithmsTest.py
+++ b/python/plugins/processing/tests/GdalAlgorithmsTest.py
@@ -62,6 +62,7 @@ from processing.algs.gdal.sieve import sieve
 from processing.algs.gdal.gdal2xyz import gdal2xyz
 from processing.algs.gdal.polygonize import polygonize
 from processing.algs.gdal.pansharp import pansharp
+from processing.algs.gdal.merge import merge
 
 from processing.tools.system import isWindows
 
@@ -2680,6 +2681,61 @@ class TestGdalAlgorithms(unittest.TestCase, AlgorithmsTestBase.AlgorithmsTest):
                  source + ' ' +
                  outdir + '/check.jpg'])
 
+    def testMerge(self):
+        context = QgsProcessingContext()
+        feedback = QgsProcessingFeedback()
+        source = [os.path.join(testDataPath, 'dem1.tif'), os.path.join(testDataPath, 'dem1.tif')]
+        alg = merge()
+        alg.initAlgorithm()
+
+        with tempfile.TemporaryDirectory() as outdir:
+            # this algorithm creates temporary text file with input layers
+            # so we strip its path, leaving only filename
+            cmd = alg.getConsoleCommands({'INPUT': source,
+                                          'OUTPUT': outdir + '/check.tif'}, context, feedback)
+            t = cmd[1]
+            cmd[1] = t[:t.find('--optfile') + 10] + t[t.find('mergeInputFiles.txt'):]
+            self.assertEqual(cmd,
+                             ['gdal_merge.py',
+                              '-ot Float32 -of GTiff ' +
+                              '-o ' + outdir + '/check.tif ' +
+                              '--optfile mergeInputFiles.txt'])
+            # separate
+            cmd = alg.getConsoleCommands({'INPUT': source,
+                                          'SEPARATE': True,
+                                          'OUTPUT': outdir + '/check.tif'}, context, feedback)
+            t = cmd[1]
+            cmd[1] = t[:t.find('--optfile') + 10] + t[t.find('mergeInputFiles.txt'):]
+            self.assertEqual(cmd,
+                             ['gdal_merge.py',
+                              '-separate -ot Float32 -of GTiff ' +
+                              '-o ' + outdir + '/check.tif ' +
+                              '--optfile mergeInputFiles.txt'])
+
+            # assign nodata
+            cmd = alg.getConsoleCommands({'INPUT': source,
+                                          'EXTRA': '-tap -ps 0.1 0.1',
+                                          'OUTPUT': outdir + '/check.tif'}, context, feedback)
+            t = cmd[1]
+            cmd[1] = t[:t.find('--optfile') + 10] + t[t.find('mergeInputFiles.txt'):]
+            self.assertEqual(cmd,
+                             ['gdal_merge.py',
+                              '-ot Float32 -of GTiff -tap -ps 0.1 0.1 ' +
+                              '-o ' + outdir + '/check.tif ' +
+                              '--optfile mergeInputFiles.txt'])
+
+            # additional parameters
+            cmd = alg.getConsoleCommands({'INPUT': source,
+                                          'NODATA_OUTPUT': -9999,
+                                          'OUTPUT': outdir + '/check.tif'}, context, feedback)
+            t = cmd[1]
+            cmd[1] = t[:t.find('--optfile') + 10] + t[t.find('mergeInputFiles.txt'):]
+            self.assertEqual(cmd,
+                             ['gdal_merge.py',
+                              '-a_nodata -9999 -ot Float32 -of GTiff ' +
+                              '-o ' + outdir + '/check.tif ' +
+                              '--optfile mergeInputFiles.txt'])
+
     def testRearrangeBands(self):
         context = QgsProcessingContext()
         feedback = QgsProcessingFeedback()