BRUSSELS - British and European Union negotiators on Monday resumed talks on their post-Brexit relationship via video-conferencing, with the focus still squarely on dividing up fishing quotas and ensuring fair competition for companies, including on state aid.

Face-to-face talks, suspended last week after a member of the EU delegation tested positive for the coronavirus, will resume in London "when it is safe to do so", said a source who follows Brexit, speaking on condition of anonymity.

Another source, an EU official, added: "The differences on the level playing field and fisheries remain major."

These issues are the key obstacles to clinching a new deal to maintain free, frictionless trade between the estranged allies after Britain's standstill transition out of the EU following Brexit completes at the end of this year.

British newspaper The Sun reported at the weekend that the negotiators were looking at a review clause that would allow a renegotiation of any new fishing arrangement from 2021 in several years' time.

An EU diplomat, a third source who spoke under condition of anonymity, confirmed that such an idea was under discussion, but added that the bloc insisted on linking it to the overall trade agreement, meaning fishing rights could only be renegotiated together with the rest of trade rules.

"We need to uphold the link between fishing and trade rules, this comes in a package," said the person.

The EU official stressed that annual renegotiation of fishing quotas was still a no-go for the 27-nation bloc. Fisheries are a particularly sensitive issue for France.

Thierry Breton, the French representative on the European Commission, the EU executive, said last week: "We shouldn't have in the Brexit deal revision clauses in one or two years, when everything would change again... We won't let that happen. We need to give our entrepreneurs predictability."

(Reporting by Gabriela Baczynska; Editing by Gareth Jones) ((gabriela.baczynska@thomsonreuters.com; +32 2 287 68 39; Reuters Messaging: gabriela.baczynska.thomsonreuters.com@reuters.net))