Allegations of torture and illegal arrest led the Philippine Supreme Court to order the military to present the accused at a hearing Friday.
The military accused the group of belonging to the New People's Army, the armed wing of the underground Communist Party of the Philippines, which has waged a 41-year insurgency that has been marked by human rights abuses and has stunted economic development.
The 43 were charged with illegal possession of weapons and explosives after Rizal provincial police chief Jonathan Miano said security forces found three handguns, three grenades and six homemade bombs in the raid on a compound where the group said it was holding a medical training seminar.
Relatives of the accused and lawyers said the suspects are not rebels but volunteer health workers serving impoverished communities with very few government medical workers.
In a statement, the lawyers said soldiers and police planted the evidence. They also questioned the search warrant, saying it was directed at a person who wasn't among the 43 and was issued by a judge from another province.
The suspects were held incommunicado, kept blindfolded, and denied legal counsel, a violation of their constitutional rights, said Edre Olalia of the National Union of Peoples' Lawyers.
Maj. Gen. Jorge Segovia, commander of the 2nd Infantry Division that has custody of the suspects, denied anyone was tortured. He said they "suffered mental anguish" caused by their arrest. He did not elaborate.
The blindfolds were necessary to prevent them from planning an escape or resistance, Segovia said.
The rebels suffered a major setback and "they will not take this sitting down so they will use every trick that they know to discredit the operation, even concoct stories," he said.
Segovia said one member of the group admitted he was a rebel and was relieved he was arrested so he could return to civilian life. Several were involved in guerrilla ambushes and raids, he said.
The Supreme Court granted a petition for habeas corpus, ordering the military to present the 43 Friday at the Court of Appeals and answer allegations of torture, evidence-planting and illegal arrest and detention.
Peace talks between the 5,000-strong rebels and the government, brokered by Norway, collapsed in 2004 after the guerrillas blamed the Philippine government for their inclusion on U.S. and European lists of terrorist groups.
President Gloria Macapagal Arroyo has ordered the military to defeat the rebels by the end of her term in June. On Internet postings, the rebels have said the deadline was illusionary and part of psychological warfare efforts.
The rebels are fighting for a communist state. After reaching their peak strength during Ferdinand Marcos' dictatorship that ended in 1986, they failed to come to terms with a new democratic government, pointing to continuing deep social divisions and abject poverty.
(By OLIVER TEVES,Associated Press Writer - Friday, February 12)