* Argentine navy ship detained in port in Ghana since Oct. 2
* Hedge fund got order to seize ship over defaulted bonds
* Argentina accuses Ghana of violating U.N. maritime treaty
BUENOS AIRES, Nov 14 (Reuters) - Argentina filed suit against Ghana on Wednesday at a U.N. maritime tribunal to demand the release of a navy ship stranded for six weeks in the African country due to a court order brought by bondholders.
The frigate ARA Libertad tall sailing ship, a naval training vessel, was detained in Ghana's eastern port of Tema on Oct. 2 at the request of hedge fund NML Capital Ltd, which says Argentina owes it $300 million on bonds in default since 2002.
Argentina says international law prohibits warships from being seized in foreign ports and has asked the Hamburg-based International Tribunal for the Law of the Sea to intervene.
"The Argentine government has presented a request for an injunction over the embargo ordered by a Ghanaian judge that violates international law," Argentine Foreign Minister Hector Timerman told reporters in Buenos Aires.
Timerman warned earlier this week that the South American country would go to the Hamburg-based court if Ghana did not lift the embargo by Tuesday.
A court statement said the tribunal would fix a date for the hearing to consider Argentina's request as soon as possible.
"No date has been set for the hearing, but it is usual that such urgent applications are heard within a month," a tribunal spokeswoman said.
Creditors including NML have won several billion dollars in damages over Argentina's default in U.S. courts, but they have largely been unable to collect because most Argentine assets are protected by sovereign immunity laws.
The litigating creditors are called holdouts because they rejected Argentina's 2005 and 2010 debt swaps, through which the country restructured about 93 percent of the roughly $100 billion it defaulted on a decade ago.
The government refers to funds like NML as "vulture funds" because they buy distressed or defaulted debt and then sue in international courts to get paid in full.
A skeleton crew of fewer than 50 sailors remains on board the Libertad after the evacuation of about 300 crewmen last month.
The ship, with its elegant, billowing sails hearkening back to the 19th century, has taken sailors on 40 expeditions since 1963. (Reporting by Alejandro Lifschitz; Additional reporting by Michael Hogan in Hamburg; Writing by Helen Popper; editing by Philip Barbara)