A Lebanese military magistrate filed terrorism charges Wednesday against 20 suspected members of the militant Fatah Islam group that has been fighting Lebanese troops in northern Lebanon, court officials said. The militants, who include 18 Lebanese, a Syrian and a naturalized Lebanese, are all in the custody of the Lebanese authorities, officials said. It was not known how or when they were arrested. Fatah Islam members have been fighting Lebanese troops since May 20 in the Palestinian refugee camp of Nahr al-Bared, near the northern city of Tripoli. Several Fatah Islam suspects have been arrested in army raids on apartments in Tripoli in the past two weeks. The suspects charged were not identified by name. It was not clear whether they included any of the militants detained in the Tripoli raids. The officials said the charges include carrying out acts of terrorism that "resulted in the killing of a number of soldiers and civilians." The charges also include forming a "gang with the aim of committing crimes against the people" and "undermining state authority and attacking civilian and military institutions," said the officials, speaking on condition of anonymity because they were not authorized to talk to the media. If convicted, the militants could be sentenced to death, the officials said. The suspects were referred to military authorities because they attacked and killed Lebanese troops. Under Lebanese law, filing charges is the first step that precedes the referral of the accused to a military prosecutor who then investigates the case. The prosecutor then either releases the suspects or raises official charges and the case goes to a military court for trial. The clashes in the north have so far left 31 Lebanese soldiers and 20 civilians dead. About 60 militants also have been killed. Nearly 25,000 Palestinians have fled the camp but several thousands have remained inside.