Discussions over proposals to expand the American military's presence in the Philippines failed to reach a deal, Filipino officials said Thursday, a day after US President Barack Obama called off a Manila visit.
The plan would allow more US troops, aircraft and ships to temporarily pass through the Philippines, an Asian military ally, at a time when Washington is refocusing its attention on Asia.
President Benigno Aquino has pushed for the deal to help modernise the Philippine military and to contain China, which he accuses of illegally laying claim to most of the South China Sea including parts of Filipino territory.
The two sides completed a fourth round of talks in Manila on Wednesday, but Filipino negotiators could not say when these will resume amid a US government shutdown.
The negotiations are at a "crucial" stage, with more work needed over the installations to be offered to the Americans, as well as the "pre-positioning" of US defence equipment, chief Filipino negotiator Pio Batino told a news conference.
"While we have narrowed down the discussions to these substantive issues, there are still gaps in our positions," he said, refusing to give details.
"We will need to work on some issues more than the others."
The other key issues tackled this week were on "ownership" and "security", a Philippine government statement said.
US Defense Secretary Chuck Hagel had said during a visit to Manila in late August that the two allies were moving towards an agreement "in the near future" and the access talks were to have been a centrepiece of Obama's visit to Manila on October 11-12.
However, Obama cancelled the Malaysian and Philippine legs of his trip on Wednesday due to the budget stand-off with Republican leaders.
Assistant Foreign Secretary Carlos Sorreta said Manila remained hopeful of concluding the agreement, though the negotiators have yet to decide on when or where to meet next.
"We believe our common interest will survive this current issue in the United States," he told reporters.
Asked about the chances of the agreement being signed by Christmas, both Batino and Sorreta said they were optimistic that there would be an eventual deal, though they could not give a time frame.
"I'm still hopeful," Sorreta said.
The United States held two large military bases near Manila until 1992, when it gave both up amid growing anti-US sentiment and a rental dispute.
A new accord in 1999 allowed troops to return to the Philippines for joint military exercises every year.
Several hundred US Special Forces troops are also on short-term assignments in the southern Philippines, where they train and advise local troops fighting Islamic militants.