Tony Blair has begun a five day trip to Africa by taking part in talks with Libyan leader Muammar Gaddafi.

The prime minister is seeking to put the continent's plight back on the international agenda ahead of the next G8 summit to be hosted by Germany.

Issues on the agenda are set to include aid, trade and climate change, issues the UK put at the top of its agenda during its own EU and G8 presidencies in 2005.

Campaigners have accused western governments of failing to deliver on the promises made at the Gleneagles talks.

And Blair is set to say that aid to developing countries has still not increased enough.

The tour kicked off with the prime minister's second visit to Libya.

He first visited the country in 2004 after Muammar Gaddafi ended his weapons of mass destruction programme.

Blair is also set to receive a warm welcome in Sierra Leone, where his deployment of British troops in 2000 was seen as a turning point in ending the country's civil war.

In South Africa he will hold talks with president Thabo Mbeki and delivers a major policy speech.

The prime minister will call for a strengthening of the African Union's ability to intervene in conflicts on the continent.

He will back moves to train and deploy more African peacekeepers in conflict-hit areas such as Burundi and the Democratic Republic of Congo.

The prime minister's official spokesman said the trip "is all about showing that we need to keep re-engaging on Africa as a whole".

And he said the 2004 visit to Libya had not been "the end of the story". "We've continued to re-engage on a political level, with ministerial visits," the spokesman said.

"We've also continued to re-engage at an economic level and today BP will be announcing that they are going back into Libya," he added.

"So re-engagement with countries - whether it's Libya or Sierra Leone or Africa in general - works."