Weah's Congress for Democratic Change, the former ruling National Patriotic Party of ex-president Charles Taylor and the Progressive Democratic Party of former warlord Sekou Damate Conneh announced their alliance in a joint statement.

"The five-year rule of the Unity Party-led government has been characterised by misrule with untold hardships and abject poverty..." read the statement.

Weah lost to Sirleaf in a run-off election in 2005, making her Africa's first democratically elected female head of state, with responsibility for rebuilding the west African nation after a series of bloody civil conflicts.

Civil wars raged in the country for 13 years, ruining infrastructure and leaving the economy in tatters.

Despite her popularity abroad, Sirleaf has been criticised at home for her decision to run in next year's election, after initially promising she would only serve one term.

She has also yet to implement recommendations by the country's Truth and Reconciliation Commission, which name her among a list of people who should not hold public office for 30 years for backing warlord-turned-president Taylor.

Legislative and presidential elections will take place in October 2011.

Source: AFP