Cornwall and the Scilly Isles have done well from the UK’s links with Europe.
Between 2000-2020 the region was set to benefit from £2.5bn in funding – money from EU cash, matched by public and private investment.
Post referendum the Government has promised to guarantee all projects signed off by this autumn.
But future initiatives worth £226m are now at risk according to Cornwall Council.
Skills training, broadband, funding for the fishing industry and major transport projects could all be threatened.
Council leader John Pollard told Sky News they are keeping the pressure up on a daily basis.
He said: We’re making sure they know there is a sense of urgency, in the sense of giving the confidence.
You know we’re talking here about a five, 10 year plan that we want to develop and fulfil, and therefore there is time but the longer it goes on the more doubt grows and we need to avoid that.
But clearly the key issue here is when are we going to come out of Europe and when we come out of Europe what are we going to do to make sure that that funding stream continues.
In recent weeks the Cornwall and Isles of Scilly Local Enterprise Partnership (LEP) and Cornwall Council have jointly written letters to the government departments currently controlling EU funding, highlighting their concerns for the future if the money they were relying on from Brussels is not guaranteed.
The correspondence highlights concerns about the future of a raft of proposed investments aimed at creating jobs and growth.
Cornwall and Scilly were earmarked for around £500m of EU investment from 2014 to 2020 to close the economic gap with other parts of Europe by growing businesses, creating jobs and boosting skills.
Officials say the Brexit vote has put a question mark over that funding, despite assurances from the Leave campaign that it would be honoured in full to 2020.
The Treasury announced on 13 August that EU-funded projects signed by the time of the Autumn Statement later this year would have their funding guaranteed.
There was a similar pledge on research funding and farm payments up until 2020, all of which has been broadly welcomed.
(c) Sky News 2016: Cornwall seeks guarantee for future funds post-Brexit