MANILA (AFP) -- Two Philippine military officers who led a failed mutiny and coup against President Gloria Arroyo could be sitting in the next Senate if early returns in national elections prove accurate.

Antonio Trillanes, 36, and Gregorio "Gringo" Honasan, 58, were both well up on the list of those contesting 12 of the 24 Senate seats, according to early returns Wednesday by the National Movement for Free Elections (NAMFREL).

Trillanes, who was among a group of junior officers who led a failed mutiny against Arroyo in 2003, was in eighth place, behind Honasan who came in seventh.

Both are awaiting trial on charges of rebellion.

Although counting has only just started in Monday's national elections, early returns indicate the opposition may take six to eight Senate seats.

While Arroyo's allies hold seven of the 12 Senate seats not contested, the fragmented opposition would need to win eight of the seats up for grabs to take control of the upper house.

The charismatic Honasan -- who once described himself as the Philippines' "resident adviser on failed coup attempts" and is awaiting trial for his involvement in a coup attempt in February 2006 -- ran as an independent.

Although the government allowed Honasan out of detention to campaign, Trillanes, who ran for the opposition, was refused.

"It's the overall message of being persecuted that has worked in Trillanes' favour," said Mahar Mangahas, president of the polling firm Social Weather Stations. "The fact that he was denied access to the media during the campaign worked in his favor. It has given voters the perception that he was being persecuted."

Despite having no platform, Trillanes used his campaign to attack the Arroyo government.

Gabriel Claudio, Arroyo's political adviser, said it was too early to comment on Trillanes' or Honasan's showing.

Some 70 percent of the 45 million registered voters turned out Monday to elect thousands of local and provincial leaders including for the 275-seat House of Representatives and half the Senate.

The Philippine National Police put the death toll as of May 15 at 130 killed and 154 injured in campaign and post-election violence.