Negotiations between the Philippines and the United States on a framework agreement for increased rotational presence of American forces in the Southeast Asian country hit a snag with differing positions on some critical or important provisions of the proposed pact, a senior military official said on Thursday.

Philippine Defense Undersecretary Pio Lorenzo Batino said in a press briefing after the fourth round of negotiations held in military headquarters Camp Aguinaldo there are a lot of work to be done as a result of these gaps.

Batino did not elaborate where the gaps occurred but acknowledged that the "substantial features" of the agreement deal with facilities, reposition of assets, and peripheral issues on definition of facilities.

"The two panels, after four rounds of negotiations, have come to understand the concerns of (both sides) and there is a recognition that both have different concerns, different requirements in the internal processes, different government requirements," said Batino.

"While we have narrowed down the discussions to these substantive issues, there are still gaps in our positions. Both panels scrutinized all the proposals that were put on the negotiating table," said Batino, the head of the Philippine panel.

He refused to dwell on the details, saying "I don't think a discussion of these details in public will be respectful of the negotiation process. So please bear with us."

The panel earlier said they need at least four to six rounds of negotiations before coming up with an agreement. The two sides are yet to set the date and venue for the next rounds of talks.