MANILA, Jan 6 (Reuters) - The Philippines' electricity grid operator is looking into conducting an initial public offering (IPO) to comply with regulatory requirements, its spokeswoman said on Wednesday, in what could be one of the country's largest public share sales.

The National Grid Corp of the Philippines (NGCP), partly owned by China State Grid Corp, was originally required by a 2008 law covering its franchise terms to sell at least 20% of its shares to the public within 10 years.

"We were previously advised that market conditions may not be ideal at the moment, but we continue to take steps to prepare for an eventual IPO," NGCP spokeswoman Cynthia Alabanza said in a text message.

Compliance with the franchise terms is the priority for the IPO, Alabanza said.

Bloomberg on Wednesday said that NGCP is planning an IPO that could raise as much as $1 billion, quoting people with knowledge of the matter, who said deliberations were at an early stage.

The Philippines energy regulator has given the NGCP a deadline to list its shares, one banker said, who also expressed doubts about whether a listing could take place this year given turbulent market conditions.

Another banker expressed doubts that the IPO could raise as much as $1 billion.

In October, fibre broadband provider Converge ICT Solutions Inc completed a $600 million IPO, the country's second largest.

In 2007, a consortium including China's State Grid, which holds a 40% stake National Grid, won the right to operate the Philippine power grid for $3.95 billion.

(Reporting by Neil Jerome Morales. Editing by Jane Merriman)