MANILA - The Philippines will maintain "close and friendly" relations with the United States under President-elect Joe Biden, a top Philippine official said on Wednesday, amid a period of strain in their decades-old alliance.

"We congratulate again the incoming president and we look forward to having close and friendly relations with the Biden administration," presidential spokesman Harry Roque told CNN Philippines ahead of Biden's inauguration.

Ties have been tested since Philippine President Rodrigo Duterte took office in 2016 and embarked on months of expletive-laden tirades against the United States and threatened repeatedly to scrap their bilateral military agreements.

Duterte has sought warmer ties with China and Russia, and took particular aim at former counterpart Barack Obama, to whom Biden was vice president. He once said he would not visit the United States, calling it a "lousy" country.

Though Duterte has spoken positively about U.S. President Donald Trump, he has remained critical of American foreign policy.

Philippine political analysts expect the Biden administration to be more vocal than its predecessor about human rights issues in the Philippines, including Duterte's signature war on drugs, during which thousands of people have been killed.

(Reporting by Neil Jerome Morales; Editing by Martin Petty) ((neiljerome.morales@thomsonreuters.com; +632 8841 8914;))