Britain's Prime Minister Theresa May is seen outside the Houses of Parliament in London, Britain March 19, 2019. REUTERS/Simon Dawson

BRUSSELS (Reuters) - British Prime Minister Theresa May must inform the other 27 EU national leaders of any plans to delay Brexit on Thursday at the latest, a senior EU official said on Wednesday.

The senior official, speaking ahead of a Thursday-Friday EU summit in Brussels that is due to discuss any Brexit postponement beyond the current leave date of March 29, said no request to go beyond that has yet arrived from London.

“To be frank, we thought today in the morning we’d have more certainty... but I’m afraid it’s still not the case,” the official said on condition of anonymity. “We have to demonstrate patience.”

“But, at the latest, I hope that during the meeting tomorrow - if there are intensions from the UK side for an extension - I hope they will be clarified tomorrow.”

All 28 EU leaders will meet together first on Thursday afternoon before May leaves the room and the others go on to discuss their next steps on Brexit without her.

“We hope that before the 27 heads of states and governments will start their discussion, Prime Minister May will address the leaders, will sketch out her plans and the assessment of the situation in the UK.”