Zimbabwean President Robert Mugabe, Africa's oldest leader at 89, has been sworn in for a new five-year term

Mr Mugabe has told critics of his re-election to "go hang" and has vowed to press ahead with nationalist policies forcing foreign firms to turn over majority stakes to black Zimbabweans.

He took his new oath of office before Chief Justice Godfrey Chidyausiku at a ceremony held in a 60,000-seat football stadium in Harare witnessed by thousands of cheering supporters, diplomats and delegations from the region.

His long-time rival and opponent in the last three elections, Morgan Tsvangirai, boycotted the ceremony.

He has denounced the 31 July election as a "huge fraud" and a "coup by ballot", alleging massive rigging by Mr Mugabe's ZANU-PF party.

Mr Mugabe and his ruling party have rejected these allegations.

This will be Mugabe's fifth term as president.

He had also served two terms as prime minister after 1980 independence ended white minority rule in the country previously known as Rhodesia.

Mr Mugabe and senior officials from ZANU-PF are the target of sanctions imposed by governments in the West, who have accused them of staying in power through massive human rights violations and vote-rigging.

Britain said today that Mr Mugabe's re-election could not be deemed credible without an independent investigation into allegations of voting irregularities.

US officials this week said the election was flawed and it had no plans to loosen sanctions until there were signs of change in the country.

The European Union will review relations with Zimbabwe given its "serious concerns" about the election, EU foreign policy chief Catherine Ashton said.

The EU's verdict on the fairness of the elections will be crucial to a decision on whether it continues to ease sanctions.