Donald Trump says Britain will vote to leave EU over migration concerns

US Republican presidential candidate Donald Trump said he thought Britain would vote to leave the European Union in June because of concerns about high levels of migration.

"With the craziness that is going on with the migration, with people pouring in all over the place, I think that Britain will end up separating from the EU, that's my opinion," Trump said in an interview with ITV television broadcast on Thursday.

Britain is due to hold a referendum on its membership of the EU on June 23. Migration is a top concern among British voters, according to opinion polls which show that British voters are divided on whether to stay in the EU.

Trump told ITV that he was not endorsing any position in the referendum. He has previously said he would clamp down on migration into the United States and has proposed building a wall along the border with Mexico to keep out illegal immigrants.

British Prime Minister David Cameron promised in 2010 to reduce the annual level of net migration into Britain to below 100,000 but it rose to 323,000 in the year to September 2015. About half the number of migrants entering Britain are from other EU countries who can move around the bloc freely under its freedom of movement principle.

ITV showed the first excerpts of its interview with Trump on Wednesday in which he said Muslims were not doing enough to report suspicious activity by extremists, comments which drew a rebuke from Britain's interior minister.