Parliament's impasse over Brexit must not be allowed to hold back Britain's financial services, City minister John Glen said on Monday.

The financial sector's traditional strengths were in good health, but the "slow and frustrating" process of seeking a deal on Britain's departure from the European Union remained a shadow, Glen said.

"The City wants and frankly deserves certainty," Glen said. We can't allow the impasse of this parliament to hold the City back."