Britain will not turn its back on the millions of citizens hoping for a better life from the Arab Spring, Deputy Prime Minister Nick Clegg will say.
In a speech to a British Council seminar in London, Mr Clegg will insist the forces driving change in the region "are here to stay".
With opposition forces in Libya closing in on Colonel Muammar Gaddafi, he is also expected to mount a strong defence of Britain's involvement in military operations against the regime.
While Mr Clegg will acknowledge the early euphoria surrounding the peaceful revolutions in Tunisia and Egypt had faded, he will say that it would be a "huge mistake" to start lowering expectations for the region.
"It is increasingly common to hear what was once hailed the Arab Spring now compared to a long, uncomfortable Arab summer," he is expected to say. "The truth is: we cannot be certain exactly how things will pan out. But the direction of travel is set. And the fundamental forces driving these changes are here to stay.
"Youth. Technology. A lack of opportunity and inclusion. Factors which have collided to create citizens who want more, who know more, who aspire to more. But who are denied it at every turn. This year that tension has hit boiling point.
"Today I want to make it absolutely clear: the UK will not turn its back on the millions of citizens of Arab states looking to open up their societies, looking for a better life."
On Libya, Mr Clegg is expected to emphasise that the Government has learned from the invasion of Iraq the importance of planning for the peace.
"The decision to support military intervention in Libya was not one the UK took lightly. Particularly not by those of us who opposed the invasion of Iraq," he is expected to say.
"We went to Libya with a clear humanitarian mandate. And tens, if not hundreds, of thousands of lives have been saved since. But, we also knew that inaction would have threatened the Arab Spring as a whole. And now, as the Colonel's fate closes in on him, what message does that send to other dictators who ignore their people's demands?"