German Chancellor Angela Merkel insisted Monday that Britain remain in the European Union, saying it was a vital gateway to the world for continental nations.

Prime Minister David Cameron has said he will hold an in-or-out referendum on Britain’s membership of the EU in 2017 if he wins a general election in May, amid tensions over immigration reform.

Foreign Secretary Philip Hammond warned Friday that Britain was prepared to walk away from talks with EU partners over the divisive issue, adding that such an outcome could influence voter sentiment on exiting the bloc.

Merkel earlier this month warned Cameron he was approaching a “point of no return” with the EU over immigration.

But she insisted Monday that Britain’s place in the union was vital and said she would do “everything I can” to ensure it remained a member.

Merkel said Britain had a different perspective on the United States and the Asia-Pacific region to continental Europeans, who she said “sometimes think if we only look at ourselves on average, that’s sufficient and we’re important enough”.