Brussels and the UK are planning to work more closely together on antitrust enforcement through sharing information and investigations, marking a rare bright spot in their post-Brexit relationship.

Under the plans being negotiated at government level, both sides will be able to sit in on confidential oral hearings with companies under scrutiny as they co-ordinate action against behaviour harming rivals. They will also co-ordinate requests for evidence from companies suspected of anti-competitive behaviour.

The proposals are being reviewed by the EU’s member states to give Brussels the green light to work with the UK in tightly-knit arrangements.

With the first six months of the UK-EU Trade and Cooperation Agreement marred by tensions over fishing rights and new trading arrangements for Northern Ireland, the plan will offer hope that London and Brussels can develop new ways of working more closely with each other.

In a further sign of improving relations, the EU last month agreed to extend grace periods on checks for chilled meats entering Northern Ireland from Great Britain.

According to two people with knowledge of the plans for closer antitrust co-ordination, Brussels and London are also working out a formal early-warning mechanism on cases regulators are likely to engage in. Such systems often form part of co-operation deals between enforcement agencies.

But the co-operation will go beyond existing deals the EU has with countries outside the bloc, highlighting a special relationship between the EU-UK regulators.

Details of the deal are still being discussed although it is hoped any agreement could be reached by the end of the year.

The UK’s competition watchdog, the CMA, said in its annual plan in March that the UK-EU post-Brexit deal included a provision to negotiate a further agreement on co-operation with the Commission and agencies from member states. The CMA will now wait to see what is agreed within the EU following conversations with member states.

The CMA is currently able to share confidential information with other regulators under the Enterprise Act, but according to a watchdog official, Brussels would need a new agreement in order to build on that kind of co-ordination with the UK.

The official said: “UK legislation already allows us to share confidential information with international partners in certain circumstances, but we understand the Commission would generally need a co-operation agreement in place to be able to do so.”

There have been signs of close co-operation between the British and EU competition authorities in recent months. Last month, antitrust investigators in Brussels and London launched a co-ordinated assault into Facebook’s alleged anti-competitive practices after opening a formal probe.

The CMA is also seeking to open a probe against the potentially anti-competitive business practices of online retailer Amazon, in a case that would closely mirror the one Brussels has already opened.