David Cameron is to meet European Union leaders for the first time since the UK voted to leave, BBC reports.
The UK prime minister will discuss the implications of the Brexit vote and the way ahead at an EU summit in Brussels.
German, French and Italian leaders said on Monday there could be no "formal or informal" talks on a British exit at this stage.
Meanwhile, Chancellor George Osborne has ruled himself out of replacing Mr Cameron as prime minister.
He said in the Times that "it isn't in my nature to do things by half-measure, and I fought the referendum campaign with everything I've got. I believed in this cause and fought hard for it.
"So it is clear that while I completely accept the result, I am not the person to provide the unity my party needs at this time."
And Health Secretary Jeremy Hunt has said the UK must remain within the EU's single market.
Mr Hunt, who is said to be considering standing for the leadership after Mr Cameron stands down, has floated the idea of a "Norway plus" arrangement outside the EU where the UK would enjoy the current trade benefits of being a full EU member while negotiating revised immigration rules.