Officials inspect the damaged St. Sebastian's Church after multiple explosions targeting churches and hotels across Sri Lanka on April 21, 2019 in Negombo, north of Colombo, Sri Lanka.

China and the U.S. have warned their citizens about traveling to Sri Lanka after a series of explosions there on Easter Sunday killed nearly 300 people, including 32 foreigners.

The warnings come as a blow to Sri Lanka's fast-growing tourism sector, which has already been hit by last year's political turmoil.

A spate of bombings on churches and hotels in Sri Lanka on Sunday killed 290 people and wounded more than 500 others. The country is under a state of emergency, and its capital, Colombo, is under curfew amid warnings of further attacks and fears of communal violence.

There has been no claim of responsibility for the attacks, but the authorities have blamed local militants with links to foreign networks.

On Tuesday, the Chinese embassy warned its citizens in Sri Lanka to stay away "in the near term" from crowded areas and pay attention to safety reminders.

"If Chinese citizens insist on going (to Sri Lanka) after this warning is issued, they will bring enormous security risks to their parties and make it difficult for the embassy to provide effective assistance," the advisory said in Chinese.

The U.S. State Department on Sunday also issued an advisory that Americans should "exercise increased caution" in Sri Lanka. "Terrorist groups continue plotting possible attacks in Sri Lanka," said the advisory, which cited tourist locations, markets, hotels, clubs and restaurants among possible targets.