US pop diva Jennifer Lopez sang happy birthday on Sunday to Turkmenistan leader Gurbanguly Berdymukhamedov in a lavish celebration at a $2-billion Caspian Sea resort in the Central Asian state.

J.Lo is believed to be the first major Western star to visit the isolated former Soviet republic, known primarily for its vast gas reserves and a dismal human rights record.

Dressed in a clingy outfit, the singer danced with half-naked backing dancers and shook her famous behind in a rare performance for the Muslim country, watched by ministers, ambassadors and chief executives of state-owned companies, all of whom applauded enthusiastically.

She later appeared in a traditional Turkmen dress to sing "Happy birthday, Mr President" along with stars from Russia, Ukraine, Turkey and China.

Berdymukhamedov's 56th birthday bash at the glitzy resort in Avaza, which means "land of singing waves", is officially tied to Turkmen cultural week, which culminated on Saturday with the opening of a yacht club at the resort and a firework display which lasted 20 minutes.

Ahead of the show, members of Lopez's entourage were busy tweeting.

"I wonder were all my Turkmenistan followers are!? Hit me up!" her choreographer J.R. Taylor wrote on Twitter account @Didntinviteme, noting that "The Turkmenistan Breeze feels amazing at night."

"Celebrating the birthday of #Gurbangulyberdimuhamedow President of #Turkmenistan... tonight!!" said the account @JLoDancers.

A representative of China National Petroleum Corporation (CNPC), which in 2009 completed a pipeline to transport Turkmen natural gas to China, told AFP that the company had organised Lopez's trip.

A report by Human Rights Watch in January described Turkmenistan as "one of the world's most repressive" regimes.

However, Berdymukhamedov has over the past years overseen an extraordinary construction boom in the country, with $2 billion invested since 2007 in Avaza alone.

It is the main resort in the country and lies near the city of Turkmenbashi (Father of all Turkmen), named after previous president Saparmurat Niyazov.

Development of the 16-kilometre (10-mile) stretch of shore in Avaza is a major project aiming to host up to 20,000 tourists annually when it is completed in 2020.

Berdymukhamedov, a former dentist, also on Saturday unveiled the country's first yacht club with 40 moorings and 44 villas, built with investment from Turkey.

"New large projects in Avaza will not only work to make it more attractive as a modern comfortable resort but serve as a push to develop tourism on the Turkmen coast," the Turkmen leader said after a boat show marked the opening.

On Friday he also oversaw the grand opening of 12 new hotels at the resort.

Berdymukhamedov has run Turkmenistan since the death of eccentric dictator Saparmurat Niyazov in 2006.

The energy-rich state holds the world's fourth-largest gas reserves and is a key producer of cotton, its staple export crop produced on irrigated fields.