The World Bank and the African Development Bank suspended millions of dollars of aid to Guinea-Bissau on Thursday, raising pressure on leaders of a military coup in the West African state to hand back power to civilians.

The move came a week after soldiers cut short a presidential election in the tiny, impoverished nation by detaining the front-runner, former Prime Minister Carlos Gomes Junior.

The two lenders said in a joint statement they were urging a speedy resolution of the crisis, and calling for the restoration of constitutional government.

Separately, the main political party PAIGC and nine others rejected an offer to join a transition to civilian rule from the coup leaders who said the process would take two years.

The World Bank has more than a dozen active projects in Bissau worth about $54 million (33.5 million pounds), according to its website. The African Development Bank has five economic and social development programmes there.

The United Nations, Washington and other world powers have condemned the self-styled Military Command for derailing the election and have urged a swift return to democratic rule.

The former Portuguese colony has seen several coups since independence in 1974. The latest was a blow to efforts by Western donors to reduce the military's meddling in politics and to counter drug-trafficking cartels using Guinea-Bissau as a smuggling hub.

The coup is the second in West Africa in less than a month, after a military ouster of Mali's president in March that left the Saharan country split in two.

DRUGS LINK

The International Committee of the Red Cross said on Thursday it had delivered medical supplies to Gomes Junior, who suffers from diabetes, twice since he was detained alongside Interim President Raimundo Pereira.

We most recently visited them on April 18 and brought medical supplies, water and hygienic supplies, spokesman Denes Benczedi said by telephone from Dakar. We are following Gomes Junior's medical condition closely, he said.

Human rights group Amnesty International said earlier this week that Gomes Junior and Pereira were being held at Mansoa Barracks, 60 km (37 miles) northeast of Bissau in a mosquito-infested small cell with no water or toilet facilities.

Gomes Junior was unpopular with military chiefs because he supported plans to reform the army, which is accused by Western security agencies of involvement in smuggling South American narcotics to users in Europe.

The Military Command said on Wednesday that it would soon create a civilian-led caretaker government to guide a two-year transition back to democratic rule, culminating in presidential and legislative elections some time in 2014.

Parliament vice-president Manuel Sherifo Nhamadjo, who came third in March's first round of the election with 15.75 percent of the vote, was named interim president on Thursday.

Gomes Junior's PAIGC party and the nine others who rejected the transition plan accused the 19 parties who have agreed to it so far of a flagrant breach of the constitution.

In a statement, the anti-coup coalition called for the release of Gomes Junior and the recognition by the military of institutions of state such as parliament and government.

(Reporting by Tom Miles in Geneva and Richard Valdmanis in Dakar; Writing by Richard Valdmanis; Editing by Andrew Heavens and Robin Pomeroy)