Index: resources/help/en/options
===================================================================
--- resources/help/en/options	(revision 1624)
+++ resources/help/en/options	(working copy)
@@ -234,10 +234,17 @@
 --ignore-turn-restrictions
 	When reading OSM files, ignore any "restriction" relations.
 
+--process-boundary-relations
+	When reading OSM files, boundary relations are processed. By default
+	they are not processed because most of the boundary relations are 
+	incomplete due to splitting of OSM files. When processing these
+	incomplete multipolygons additional artificial boundary lines are 
+	created on the tile bounds. 
+
 --ignore-osm-bounds
 	When reading OSM files, ignore any "bounds" elements.
 	With this option selected generate-sea sometimes works better,
-	but routing accross tiles will not work.
+	but routing across tiles will not work.
 
 --preserve-element-order
 	Process the map elements (nodes, ways, relations) in the order
Index: src/uk/me/parabola/mkgmap/reader/osm/xml/Osm5XmlHandler.java
===================================================================
--- src/uk/me/parabola/mkgmap/reader/osm/xml/Osm5XmlHandler.java	(revision 1624)
+++ src/uk/me/parabola/mkgmap/reader/osm/xml/Osm5XmlHandler.java	(working copy)
@@ -109,6 +109,7 @@
 	private final boolean makeOppositeCycleways;
 	private final boolean makeCycleways;
 	private final boolean ignoreBounds;
+	private final boolean processBoundaryRelations;
 	private final boolean ignoreTurnRestrictions;
 	private final boolean linkPOIsToWays;
 	private final boolean generateSea;
@@ -174,6 +175,7 @@
 			minimumArcLength = null;
 		frigRoundabouts = props.getProperty("frig-roundabouts");
 		ignoreTurnRestrictions = props.getProperty("ignore-turn-restrictions", false);
+		processBoundaryRelations = props.getProperty("process-boundary-relations", false);
 		reportUndefinedNodes = props.getProperty("report-undefined-nodes", false);
 		String deleteTagsFileName = props.getProperty("delete-tags-file");
 		if(deleteTagsFileName != null)
@@ -600,7 +602,13 @@
 			long id = currentRelation.getId();
 
 			relationMap.put(id, currentRelation);
-			currentRelation.processElements();
+			if (processBoundaryRelations == false &&
+			     currentRelation instanceof MultiPolygonRelation &&
+				 ((MultiPolygonRelation)currentRelation).isBoundaryRelation()) {
+				log.info("Ignore boundary multipolygon "+currentRelation.toBrowseURL());
+			} else {
+				currentRelation.processElements();
+			}
 
 			List<Map.Entry<String,Relation>> entries =
 				deferredRelationMap.remove(id);
Index: src/uk/me/parabola/mkgmap/reader/osm/MultiPolygonRelation.java
===================================================================
--- src/uk/me/parabola/mkgmap/reader/osm/MultiPolygonRelation.java	(revision 1624)
+++ src/uk/me/parabola/mkgmap/reader/osm/MultiPolygonRelation.java	(working copy)
@@ -98,6 +98,10 @@
 		copyTags(other);
 	}
 
+	public boolean isBoundaryRelation() {
+		return getTag("boundary") != null;
+	}
+	
 	/**
 	 * Retrieves the mp role of the given element.
 	 *