EU members states are looking to draw up a "code of conduct" for dealing with the British government amid fears Boris Johnson could try to play them off against each other.
The code could require meetings with the UK concerning European affairs to be reported to Brussels, which would keep tabs on British lobbying of countries.
Since the EU referendum the UK government has made no secret of the fact it tries to play member states off against each other to achieve its aims in the EU capital.
But following Brexit the UK has extended its lobbying to member states in a bid to make up for its lost influence and lack of a seat at the table.
Without any MEPs, or a seat on the European Council, ambassadors' committees, or ministerial bodies, the UK relies on EU member states to carry its message into the room.
But there is concern in Brussels that British lobbyiong could be getting out of hand.
An EU source said the idea of a code of conduct had been discussed between member states at a meeting in Brussels.
The basis for the approach appears to be a European Council decision from December 2020 calling on member states to keep each other in the loop on discussions with the UK.
But some EU diplomats downplayed suggestions that this amounted to a formalized code.
Commenting on the idea, David Henig, the UK director of the European Centre For International Political Economy think-tank said: "The EU had something similar for member state contacts with the US during TTIP talks.
"[It] didn't stop the contacts, not all of which were reported to the EU, but did make some think twice."
The move comes as the UK and EU are still locked in talks about the implementation of the Northern Ireland protocol.