The EU is urging Britain to drop the “political rhetoric” around Brexit as historic talks on the future trading relationship open in Brussels.

As an army of 100 officials led by Britain’s chief Brexit negotiator, David Frost, descend on the Belgian capital on Monday, senior EU diplomats are warning that if the political temperature continues to rise over Brexit in the UK it will risk smothering talks.

They are concerned about the political relationship between the UK and the EU, characterised by furious language including warnings that each side will “rip” each other apart, and the second relationship – that among officials tasked with examining the deeper, drier technical complexities of disentangling and reimaging 47 years of joint laws and regulations.

As soon as the debate around Brexit moves to the “tunnel” of technical detail and away from the politics, the quicker a space can be opened up for a deal, say sources.

They warn the agreement will affect people and business across 28 countries and it behoves both sides to get away from politics and do a good deal for both sides.

The deadline to reach a deal is the end of the year, with key elements including fishing rights, due to be resolved by 1 July, leaving just three months for the opposing sides to resolve headline differences for a “stocktake” in mid-June.

Detailed negotiations on potential tariffs are impossible in this timeframe.

That means the only way to get a deal is to have close alignment on regulations on both sides, said a source.

They said the most contentious issues will not be tariffs, quotas and market access but “governance and dispute resolution”, given that the UK has comprehensively rejected any role for the European institutions or the European court of justice.

Brexit negotiations schedule, round one. Photograph: European Commission

Among the issues slated as easier to resolve are transport, chemical waste and Horizon Europe, the science research programme.

The EU is said to have abandoned any hope of “dynamic alignment” whereby the UK would agree to abide closely to EU regulations as they evolved in coming years. That is now considered a dead topic, following the publication of the UK’s trading mandate last week.

Fisheries, so emblematic on the British side of the leave vote, is expected to be one of the trickiest issues politically with Denmark, France, Spain, the Netherlands and Ireland insisting on continued access to British waters.

The two sides have already clashed over the issue but EU sources say they don’t need a full agreement by July, merely an outline of a deal which will give a “hint” to the fishing communities that their 2020 fishing rights are secure.

The areas to be discussed on Tuesday and Wednesday are: trade in goods; trade in services; transport energy and civil nuclear co-operation; fisheries; a level playing field for open and fair competition; law enforcement and judicial co-operation; participation in union programmes; mobility and social security; cooperation in programmes such as Horizon Europe; and governance and dispute resolution.

According to the agenda, published by the EU, the talks will start with a meeting of lead negotiators on Monday, moving to an opening plenary session at 4.30pm.

The group is so large that from Tuesday negotiators will be moved from the Berlaymont headquarters of the European commission to a conference centre. The talks will be split into 11 groups covering everything from trade and nuclear energy to fisheries and state aid.

This week’s talks will be the first of 10 rounds that will take place every three weeks, alternating between Brussels and London.