Libanan said that during the raid late last month, the six monks could not present their working visas.
"No less than the management of the temple admitted that the Taiwanese monks were doing missionary work at the temple without pay," Libanan said in a statement, adding that the monks were compensated with free board and lodging at their temple in Paco, Manila.
However, Libanan stressed: "The fact that the monks were rendering services to the temple without pay is no excuse for them not to obtain a missionary working visa from the BI as required by the Philippine Immigration Act."
The Immigration chief added that it was the obligation of the temple management to petition the BI to issue missionary working visas to the Taiwanese monks, who were supposed to be under the care, supervision or employ of the temple.
"We are warning other foreigners who come here to perform missionary or religious work to apply for the appropriate visa because the law does not exempt them from complying with our immigration laws," Libanan said.
Aside from being fined P10,000 each, Libanan also issued a stern warning to the monks that a repetition of their offense would be dealt with severely.
He also directed the monks to update their stay and apply for missionary working visas with the BI within 15 days upon receipt of his order.
BI technical assistant for intelligence Victor Boco explained that under Section 9 (g) of the Philippine Immigration Act, foreign religious preachers or workers who visit the Philippines should apply for a missionary visa.
Boco clarified that a missionary visa was different from the commercial or pre-arranged employment visa that the BI issues to expatriates employed in the Philippines.