NEW YORK (NYTIMES) - Rear Admiral Robert Gilbeau, the first US Navy admiral ever convicted of a federal crime while on active duty, was sentenced on Wednesday to 18 months in prison for lying to investigators about his involvement in a bribery scandal that has ensnared numerous Navy officers.

Gilbeau pleaded guilty in June to making false statements when he told agents that he had never received any gifts from Leonard Glenn Francis, a Malaysian ship supplier based in Singapore at the centre of a bribery scandal.

Francis, who is known as Fat Leonard, has been charged in the case with 19 Navy officers. Ten of the officers have pleaded guilty, mostly for accepting Leonard's bribes of trips and prostitutes in return for routing ships to ports where he could ring up millions of dollars in fraudulent charges.

According to the government's sentencing memorandum, Gilbeau received cash and gifts from Francis beginning in 1997, including visits to nightclubs, karaoke bars, restaurants and luxury hotels, and the use of prostitutes.

Prosecutors said the admiral had approved invoices that grossly overbilled the Navy and had destroyed documents and computer files after Francis, who is cooperating with the authorities, was arrested in 2013.

Gilbeau is the highest-ranking officer convicted in the scheme so far. As many as 30 other admirals remain under investigation for possible ethical violations in their dealings with Francis, including some that occurred before they rose to that rank.