ASHGABAT, Dec 7 (Reuters) - Fresh tremors rocked Turkmenistan on Thursday, a day after the Central Asian state was hit by a powerful earthquake but officials said it caused no casualties or significant damage.

A spokesman for Turkmenistan's national civil defence unit told Reuters that mild tremors had been recorded at 0353 GMT in the oil producing towns of Balkanabad and Kazanzhik, 500 km (310 miles) west of the capital Ashgabat.

The jolts came after most people in Balkanabad (formerly Nebit Dag), which produces 80 percent of Turkmenistan's oil, spent the night on the street fearing further quakes.

A spokesman for Turkmenistan's civil defence headquarters told Reuters earlier that tremors which hit Ashgabat at 11 p.m. (1700 GMT) on Wednesday had measured four on the 12-point Soviet-era scale.

He said the quake measured seven on the 12-point scale at its epicentre in the Caspian Sea some 800 km (500 miles) west of Ashgabat and mainly affected sparsely populated areas on the coast and the border with Iran.

Turkmen officials would not confirm a report by Chinese state television which said the quake had killed 11 people and injured five. The television report monitored in Beijing gave no details and did not specify the source of the information.

Earlier, an official with the China Seismological Bureau told Reuters the earthquake measured 7.4 on the open-ended Richter scale.

A spokeswoman for the U.S. Geological Survey in Golden, Colorado, which monitored the quake, said earlier on Thursday it measured 7.2. on the Richter scale at the epicentre.

CALM

Residents of Ashgabat, situated in a seismic zone, barely reacted to Wednesday's tremor and most of them calmly stayed in their homes. Small tremors are common in the country.

The Turkmenistan spokesman said the quake measured five on the 12-point scale in the oil refining town of Turkmenbashi on the Caspian Sea but no casualties or major damage were recorded.

The quake was also felt in other parts of the former Soviet Union, including Azerbaijan's capital Baku and the Armenian town of Spitak, destroyed by a 10-point quake in 1988 which killed 25,000 people.

The Uzbek Caspian town of Nukus experienced a quake measuring four on the Soviet scale while milder tremors rocked Tashkent, Samarkand and Bukhara.

Light shocks were felt in Western Kazakhstan as well, emergencies ministries in both countries said.

Ekho Moskvy radio in Moscow said light traces of the Central Asian quake could be felt in the Russian capital and St Petersburg.

According to different accounts, between 45,000 and 100,000 people died in a major earthquake in Ashgabat in 1948.