The British government has denied it will "tear up" its Withdrawal Agreement treaty with the European Union, but tensions remain over a future trade deal as the 8th round of talks began in London on Tuesday.

The latest negotiations do not promise any significant breakthrough, however, mostly because of entrenched positions on state subsidy rules and fishing rights.

The United Kingdom left the EU on Jan 31 this year, under the terms of a negotiated divorce deal, ending 47 years of British membership.

The focus is now on the trading relationship beyond the transition period that ends on Dec 31, and, as an extension has been ruled out, the time remaining to broker a deal is short.

The UK government has sought to increase the pressure on the EU to make progress in the talks by setting a new mid-October deadline for negotiations to succeed.

Prime Minister Boris Johnson said ahead of the talks "if we can't agree by then, then I do not see that there will be a free trade agreement between us."

Senior EU officials this week became concerned by a Financial Times report that new Brexit legislation proposed by the UK government could override key elements of the Withdrawal Agreement, and said this could hamper talks.

The EU has stated that the "full implementation" of the Withdrawal Agreement was a "prerequisite for the negotiations on the future partnership" between the bloc and the UK.

But a Downing Street spokesperson said the new law－the UK Internal Market Bill that will be tabled on Wednesday－would only make "minor clarifications in extremely specific areas".

BBC News reported that the new law will certify that goods from Northern Ireland can continue to have access to the UK market and ensure EU subsidy rules, which will continue to apply in Northern Ireland, will not apply in the rest of the UK.

Ahead of the meeting, the UK's chief negotiator, David Frost, warned his EU counterpart, Michel Barnier, that progress must be made. Frost called for "realism", saying there was "still time" for the two sides to agree a deal.

Frost said: "Today, I will sit down with Michel Barnier and drive home our clear message that we must make progress this week if we are to reach an agreement in time.

"We have now been talking for six months and can no longer afford to go over well-trodden ground.

"We need to see more realism from the EU about our status as an independent country."

Frost said the UK position comes from the "fundamentals of being a sovereign state" and called for the EU to "fully recognize this reality".

"If they can't do that, in the very limited time we have left, then we will be trading on terms like those the EU has with Australia, and we are ramping up our preparations for the end of the year."