Down an avenue named after Genghis Khan, up to the third floor of a Soviet-era government ministry and down a creaking wooden hallway, its carpet frayed and faded with the dust and the sun of the steppes, one office door has a freshly minted sign: Maritime Administration.

In a one-room office, with whirring computers, a fax machine at the ready and model ships for décor, two civil servants oversee the Mongolia Ship Registry, an international service that offers quite competitive fees and no restrictions on the ownership of any ship.

Mongolia, the world's largest landlocked country, with its capital almost 1,000 miles from an ocean beach, is the latest entry in the business of flags of convenience. With Mongolia's red, yellow and blue colors now flying on 260 ships at sea, this unlikely venture is part business, part comedy and part international intrigue.

''We earned the treasury about $200,000 last year,'' Bazarragchaa Altan-Od, head of the Maritime Administration, said, slightly tense for his first interview with the world press. ''We have 20 to 30 new registrations every month. The number is increasing.''