MANILA, Philippines (AP) — The release of four police officers abducted by Filipino communist guerrillas has sparked hopes that stalled peace talks will resume, a government official said Wednesday, although major obstacle remains.

New People's Army rebels released the police officers they seized in a July 10 attack on a police station in the remote southern town of Alegria in Surigao del Norte province, saying it was a goodwill gesture to promote peace negotiations and a response to the appeals by the policemen's families.

Presidential peace process adviser Teresita Deles said the move "constitutes a potential building block" toward resuming the talks.

"We invite the rebels to come to the table to find common solutions to our problems in peaceful dialogue," Deles said.

Presidential spokesman Edwin Lacierda urged the rebels to resume formal or informal negotiations with the government without conditions, a position echoed by the military.

"We are prepared to fight but that's the last thing we want," military spokesman Lt. col. Ramon Zagala said. "If there's a chance to return to the negotiating table and prevent more divisiveness in our country, why not?"

But Deles said the government was still against a rebel demand that detained comrades be released as a pre-condition to the talks resuming. The government stance led to the collapse of the talks, which are brokered by Norway.

"We're not open to discussing releases at this point," Deles said.

The rebels have been fighting since 1969 in one of Asia's longest-running Marxist insurgencies. Their numbers have dwindled, but they are still regarded as the country's most serious security threat.

They have intensified attacks against state forces, large mining companies and agricultural plantations in recent years, further dimming prospects of a resumption of peace negotiations. In contrast, government talks with the largest Muslim rebel group in the country progressed and led to the signing of a new Muslim autonomy deal in March.