PARIS — Satellite fleet operator Thaicom of Thailand said Jan. 2 it would purchase an equity stake in a Chinese company to sell Thaicom’s IPStar broadband satellite capacity in China, a development that could unlock China’s vast potential as an IPStar market eight years after the satellite’s launch.

In a filing with the Stock Exchange of Thailand, Thaicom said it would close the transaction with Vastsuccess Holdings Ltd. of China by March 31. The company did not disclose the terms of the transaction or the ownership stake it would have in Vastsuccess.

Vastsuccess, a wholly owned subsidiary of Synertone Communication Corp., will have the right to purchase all IPStar capacity over China and to use IPStar ground gateways until the satellite is retired.

Launched in August 2005, IPStar, also known as Thaicom 4, uses Ku-band frequency to provide Internet access in Southeast Asia and the wider Pacific Ocean region, with Australia being one of its largest national markets. IPStar has up to 45 gigabits per second of throughput and was built to operate at least until 2020.

In a Dec. 30 filing with the Hong Kong Stock Exchange, Synertone — whose corporate address is in the Cayman Islands — said Vastsuccess would pay Thaicom a $600,000 down payment on the first year’s service within three days of the deal’s signature. If the agreement is not concluded by June 30, it will expire, Synertone said.

Synertone said Thaicom would be eligible to purchase up to 10 percent of Vastsuccess, and that the minimum service period under the contract would be 9.5 years.

Thaicom said about 24 percent of IPStar’s total capacity is available to Chinese customers.

“China is an important market for Thaicom, and I am pleased that Thaicom and our partners have achieved this key milestone of IPStar business in China together,” Thaicom Chief Executive Suphajee Suthumpun said in a statement.

Thaicom and Vastsuccess have secured licenses to operate in China from China Telecom Satellite Comunications Ltd., Thaicom said. Thaicom, China Telecom and China Satellite Communications Corp. in 2009 had concluded an IPStar marketing agreement. Vastsuccess will replace Thaicom for China IPStar sales under the new agreement.

Peter B. de Selding was the Paris Bureau Chief for SpaceNews.