MANILA - A senator on Tuesday scored the Bureau of Immigration (BI) for what she calls "excessive use of authority" in arresting and detaining a 71-year-old Australian nun for alleged engagement in "partisan political activities."

Senator Nancy Binay said the bureau should focus on running after Chinese drug cartels, smugglers, and foreigners involved in child pornography instead of Sister Patricia Fox who has been helping farmers and indigenous peoples in the Philippines for 27 years.

"The Bureau of Immigration used excessive authority in connection with the arrest of Sister Patricia, and has acted on a mistaken perception plucked from an imaginary threat. Ang tanong e how can a 71-year old nun be a threat to society?" she asked.

Fox, who has been active in human rights fact-finding missions in Mindanao, was arrested by Immigration authorities Monday following a mission order issued by BI Commissioner Jaime Morente. She was released on Tuesday "for further investigation."

Various groups slammed the BI's arrest of Sister Fox, which came after the deportation of a European Socialist Party official for similar reasons. They fear that the government has begun a crackdown on foreign activists.

But Immigration spokesperson earlier said that the basis for Fox' arrest was intelligence reports about her recent activities. She insisted that foreigners should observe limitations of the exercise of their political rights while staying in the country.

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"Siguro ang kailangan pagtuunan ng pansin ng BI eh 'yung mga illegal aliens na nagpapasok ng droga, 'yung mga involved sa human smuggling at child pornography at 'yung nasa terror list ng AFP," Binay said.