* EU cut relations with Bissau after April coup
* Transitional president says needs international backing
* Tiny West African state a haven for cocaine smugglers
DAKAR, March 1 (Reuters) - Elections that coup-stricken Guinea-Bissau was to have held in May have been postponed after West African leaders prolonged the mandate of its caretaker government by seven months.
The delay underscores the challenges faced by transitional authorities in the tiny West African nation - a known narcotics trafficking hub - following a military coup in April 2012 that prompted international partners to freeze aid.
Heads of state from West Africa's 15-nation ECOWAS bloc extended the transitional period in Guinea-Bissau until Dec. 31, according to a communique issued late on Thursday after a summit in Ivory Coast.
It said ECOWAS was asking transitional President Manuel Serifo Nhamadjo to propose a revised timeline for elections to be held before the end of the year, instead of May as planned.
The former Portuguese colony was thrown into turmoil last year after soldiers ousted interim President Raimundo Pereira and Prime Minister Carlos Gomes Junior days before an election Gomes Junior was favoured to win.
The military junta handed power back to a civilian leadership led by Nhamadjo in May under a deal brokered by ECOWAS, but which was criticized by the United Nations, the European Union and the CPLP grouping of Portuguese-speaking states as dealing too softly with the coup leaders.
The European Union - once a source of hundreds of millions of dollars in aid to the state - has so far refused to recognise Nhamadjo's administration, a decision the interim president says is hindering election preparations.
Guinea-Bissau's parliament is also in disarray, with members loyal to ex-premier Gomes Junior calling for his return and blocking the organisation of any polls that could exclude him.
Guinea-Bissau is rich in natural resources, including minerals, cashews, and some of the world's best fishing offshore, but political instability has hindered investment and kept most of its 1.6 million people mired in poverty.
Thin law enforcement and reported state complicity have allowed South American cartels to use its scores of mangrove-lined islands as a transhipment hub for cocaine bound for the markets of Europe for more than a decade.
Army chief General Antonio Indjai, who runs a military widely suspected of complicity in the drug trade, has been accused of leading the April coup and the EU says he still holds sway. (Reporting by Richard Valdmanis; Editing by Alistair Lyon)