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Police armed with truncheons, shields and a fire hose clashed with more than 100 left-wing activists who rallied at the U.S. Embassy in Manila on Wednesday to oppose a visit by President Barack Obama and an expected security pact that would increase the American military presence in the Philippines.

Some of the protesters carried paper U.S. flags with the message: "Obama not welcome."

Obama, who landed in Japan on Wednesday, is due to visit South Korea, Malaysia and the Philippines over the next five days as part of a wider attempt to "rebalance" and "pivot" toward Asia.

Protesters shout slogans during a rally at the U.S. Embassy in Manila on April 23, 2014 against next week's visit by President Barack Obama. Bullit Marquez / AP

— The Associated Press contributed to this report