LONDON (Reuters) – Britain will pay “not a penny more, not a penny less” than what the government thinks its legal obligations are to the European Union as the country leaves the bloc, foreign minister Boris Johnson said on Friday.

Talking to BBC Radio Four, Johnson said his comment that the EU could “go whistle” on its demands for payment was in response to being asked whether Britain would pay “100 billion euros or pounds”, and not a suggestion that the government would not pay.

A financial settlement is set to be one of the most difficult issues to resolve in negotiations to unravel more than 40 years of union, and the EU has said it is one of three areas the two sides must make progress on before starting talks on a future relationship, including trading arrangements.

“Some of the sums that I’ve seen seem to be very high. Of course, we will meet our obligations,” Johnson said. “We should pay not a penny more, not a penny less of what we think our legal obligations amount to.”