LONDON — Britain should seek to postpone its exit from the European Union if talks drag on during the next few months, an influential committee of lawmakers concluded on Sunday.

The panel’s recommendation split its members, some of whom disowned the document, and illustrated the growing concerns in Parliament over the pace of the negotiations.

The report came ahead of a summit meeting this week at which European Union leaders are expected to agree, in principle, on a standstill transition period of slightly less than two years to prevent Britain’s economy from suffering the effects of a “cliff edge” departure from the bloc next March, when it is formally scheduled to quit.

But even that transition would be conditional on the success of broader discussions on the withdrawal, known as Brexit. The talks are due to end in the fall, but that deadline looks very difficult to meet, particularly because of the complexity of avoiding the introduction of a hard border in Ireland.