The British government pledged Saturday to match European Union funding for farmers, universities and infrastructure projects after Britain leaves the bloc, to stem fears that key sectors will be left struggling.

The commitment, intended to address uncertainty over the impact of the June 23 vote for Brexit, could cost around £4.5 billion ($5.8 billion, 5.2 billion euros) a year, finance minister Philip Hammond said. 

The commitment applies to agricultural funds until 2020, structural and investment projects signed before the government's budget update this autumn, and university bids won under the Horizon 2020 research and innovation programme.

"We recognise that many organisations across the UK which are in receipt of EU funding, or expect to start receiving funding, want reassurance about the flow of funding they will receive," Hammond said in a statement.

"That is why I am confirming that structural and investment funds projects signed before the Autumn Statement and Horizon research funding granted before we leave the EU will be guaranteed by the Treasury after we leave. 

"The government will also match the current level of agricultural funding until 2020, providing certainty to our agricultural community, which play a vital role in our country."

The cost will depend on the level of applications for funds, and on when Britain leaves the EU. 

The government has said it will not trigger the two-year withdrawal process before the end of this year.

"Around about £4.5 billion a year would be the level we would expect," Hammond said.

Campaigners for Britain to stay in the EU in the June 23 referendum had highlighted the funding benefits of membership to key sectors such a farming and research.

But the Brexit camp said any shortfall could be covered by ending Britain's contributions to the EU budget, which stood at about £12.9 billion in 2015, after the rebate.

Projects covered by the government's guarantee include a new facility at the University of Manchester to develop research into graphene -- a material which scientists say could transform consumer electronics -- using £5 million from the European Regional Development Fund.