LONDON, May 14 (Xinhua) -- The chief Brexit negotiator for British Prime Minister Theresa May is traveling to Brussels on Tuesday to discuss changes to the political declaration on Britain's future relationship with the European Union (EU).

The latest travel by Olly Robbins comes amid the ongoing cross-party talks between the British ruling and opposition parties to break a current impasse.

The declaration, published with the British government's withdrawal agreement that has been vetoed by the parliament three times, sets out the parameters for the future relationship between Britain and the EU. It is not legally binding.

Media reports said Robbins will explore how quickly changes could be made to the political declaration, if the government and Labour can reach an agreement.

As Conservative-Labour talks are expected to continue on Tuesday to find a formula to end Britain's Brexit deadlock, officials have revealed a record for the British Parliament. The current session of parliament is the longest since the English Civil War in the 1600s.

The continuing impasse over Britain's departure from the EU means that till Friday, the House of Commons had sat for 298 days, researchers at Parliament's library said.