Reality Check: Do 44% of UK exports go to the EU?

The claim: EU countries buy 44% of everything we sell abroad.

Reality Check verdict: The 44% figure is probably a bit of an overstatement, but not by more than about two percentage points.

Leave campaigner Bernard Jenkin MP has written to the UK Statistics Authority chairman Sir Andrew Dilnot to challenge the government's claim that 44% of UK exports go to the European Union.

"The true figure is bound to be less than that, given the 'Rotterdam effect'," Mr Jenkin says.

The Rotterdam Effect is the phenomenon of some exports being classified based on the port from which they are shipped rather than their final destination.

The concern is that some exports from the UK are classified as going to the Netherlands, when they are, in fact, going to Europe's biggest port, in Rotterdam, to be shipped around the world.

Sir Andrew replied saying that while it is hard to quantify the level of the Rotterdam Effect, it was unlikely to involve more than 50% of goods exported to the Netherlands which would not knock more than two percentage points off the government's figure of 44% of UK exports going to the EU. That "suggests that the statement in the government leaflet is not significantly affected by it".

It may seem odd that the impact is so small, given that the Netherlands is the third biggest customer for UK exports, behind the USA and Germany. But remember that the Rotterdam Effect only affects exports of goods, while the 44% figure is for both goods and services.

Sir Andrew did suggest that a more prominent note in the statistics about the Rotterdam Effect would be helpful. In evidence to the parliamentary committee chaired by Bernard Jenkin, he said that would be particularly important to people interested in the level of exports to the Netherlands rather than the whole EU.

Read more: The facts behind claims in the EU debate