MANILA -- A US senator who was barred from entering the Philippines for supporting President Rodrigo Duterte's detained critic said Friday he would not be silenced by "strongman tactics."

Duterte is "sorely mistaken" if he thinks he can silence his critics, said Democratic Senator Edward Markey from Massachusetts.

Markey is among 3 US lawmakers barred from entering the Philippines for criticizing the continued detention of Sen. Leila de Lima on drug dealing charges.

"I stand with the people of the Philippines and with my state’s vibrant Filipino-American community in fighting for the highest democratic ideals and against the strongman tactics of the Duterte government," he said.

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Manila imposed a travel ban against several US lawmakers after Washington barred the entry of De Lima's jailers in American territory. Duterte also threatened to require visas for Americans traveling to the Philippines.