MANILA, Philippines (AP) _ Philippine authorities said Monday that they have arrested two American brothers for suspected links to terrorism, as the country remained on alert over the reported presence of foreign Muslim militants in the south.

Michael Ray Stubbs and his brother James, a convert to Islam, have been held at an undisclosed location since they were arrested earlier this month in the town of Tanza in Cavite province, 21 miles southwest of Manila, an immigration official said on condition of anonymity.

The official said the brothers were of Middle Eastern origin but gave no other details. The authorities did not disclose the exact charges the men could face or provide details about their alleged links to terrorism.

Their hometowns were not available and the U.S. Embassy could not immediately be reached for comment. More information was expected to be released Tuesday.

The arrests came as the government warned earlier this month that Indonesian members of the Southeast Asian terror group Jemaah Islamiyah have been training Filipino rebels in bomb-making and other tactics in the south of the country.

Jemaah Islamiyah, which has links to al-Qaida, is suspected of several terror attacks, including last year's Bali bombings that killed 202 people.

Philippine authorities say the group was involved in a series of December 2000 bombings that killed 22 people and injured more than 100 in the capital, Manila.

Since then, police and military forces have increased the security at ports, airports, train stations and other public places.

The Philippines previously has detained and deported foreigners on suspicion of terrorism.

In September, a Jordanian national, Mahmoud Afif Abdeljalil _ believed to be a close associate of Osama bin Laden's brother-in-law _ was arrested in the southern city of Zamboanga on charges of having an expired visa. After he was interrogated, he was ordered deported.

The previous year, immigration officials deported two Jordanian men, also suspected of having links to terrorists, after failing to find enough evidence to prosecute them.