The United Kingdom's chief Brexit negotiator has said Britain is not "scared" to walk away from talks with the European Union over future trading relations between the UK and the bloc beyond the end of the year without reaching an agreement.

Since Britain left the bloc at the end of January, it has been in a transition period where it remains subject to EU regulations, with the aim of the two sides coming to terms by the end of 2020, a deadline imposed by Prime Minister Boris Johnson's government.

So far, however, talks have failed to make significant progress, and after the most recent round the EU's chief negotiator, Michel Barnier, said he was "worried and disappointed" by the UK's lack of flexibility.

British negotiator David Frost told the Mail on Sunday that Britain would leave at the end of the year, "come what may", and "a lot of what we are trying to do this year is to get (the EU) to realize that we mean what we say and they should take our position seriously".

Last year, Johnson won the general election campaign on a promise to "Get Brexit Done" and spoke of an "oven-ready" deal, but time is now running out, with little sign of compromise, and he has said with or without a deal, "we will prosper mightily one way or the other".

Frost said the current government would not repeat the negotiating mistakes of Johnson's predecessor Theresa May.

"I don't think that we are scared of this at all," added Frost.

Speaking on the BBC, Foreign Secretary Dominic Raab backed up Frost's remarks, saying this week was "the EU's best moment to strike a deal" and that the raised stakes should be a "wake-up call" for Brussels.

The key issues holding back discussions are fishing rights and post-Brexit state aid to British industries.

Brussels says it wants EU member states to have access to British waters in return for the UK's fishing industry having access to EU markets. Raab accused the EU of wanting to keep British access to European waters "permanently low".

According to House of Commons figures quoted by German broadcaster DW in 2019, the UK's fishing industry employs 24,000 people, contributing 1.4 billion pounds ($1.8 billion) to the economy, which is 0.12 percent of GDP and less than 0.1 percent of Britain's workforce.

British fishermen export 80 percent of what they catch, and 70 percent of fish eaten in the UK is imported.

The EU is also concerned post-Brexit state aid to industries will give British industries an unfair advantage. Raab said this was something that was "an absolute critical element of policy making" which should be the decision of British politicians.

Industries do not seem to share government optimism. Rod McKenzie of Britain's Road Haulage Association said the lack of clarity meant the government was "sleepwalking to a disaster.

"The supply chain on which we are all dependent to get the things we need could be disrupted and there is a lack of government focus and action on this," he added.