David Cameron will urge the world to continue to give support to the emerging democracies of the Arab Spring as he addresses the United Nations General Assembly in New York.
And the Prime Minister will offer direct assistance on security and finance to Egypt in his first meeting with president Mohamed Mursi since his election in June.
Mr Cameron will say the UK stands ready to give Egypt expert advice on maintaining security in the sensitive Sinai area, where government troops have clashed with militants in recent weeks.
He will promise to cut through Brussels red tape which is delaying the repatriation to Egypt of assets valued at up to #100 million, stolen by the regime of deposed president Hosni Mubarak.
In his keynote speech to the General Assembly, Mr Cameron is expected to voice optimism about the prospects for Egypt and its neighbours in North Africa and the Middle East in the wake of the uprisings which forced Mubarak and other long-serving dictators from power.
While Britain sees little prospect of an imminent breakthrough on the continuing conflict in Syria, Mr Cameron is also expected to press world leaders gathered in New York to support humanitarian efforts to help those caught up in the violence.
A senior UK Government source said that Mr Cameron recognises the "concerns and worries" felt in Western capitals over the election of people with Islamist backgrounds to positions of power in Arab Spring states.
But the source said the Prime Minister believes the new governments emerging in the region should be judged by their actions, citing moves by Mr Mursi - who came to prominence as a member of the Muslim Brotherhood - to clamp down on Islamist militants in the Sinai.
Reining in radical activities is thought to be a key to calming Israeli concerns over security on its borders, as well as paving the way to the return of economically vital tourists to Red Sea resorts.
Chief of the Defence Staff Sir David Richards is to visit Cairo in the autumn for high-level discussions on what Britain can do to assist with security in the Sinai.
And Mr Cameron will today tell Mr Mursi that the UK is ready to work with Egypt on tackling issues fuelling tension and unrest in the area, including by offering security advice and mentoring.