The U.S. Embassy in Jakarta has issued a warning to Americans about a potential threat against U.S. associated banks and hotels in Indonesia's second-largest city, Surabaya.

An embassy spokesperson said Sunday there was nothing linking the warning with AirAsia Flight 8501.The plane crashed into the Java Sea a week ago after taking off from Surabaya, killing all 162 passengers and crew on board. The U.S. Navy is taking part in an international effort to recover bodies and locate the wreckage.

The alert was issued to U.S. citizens on Saturday without giving details.

Indonesia's national police spokesman Brig. Gen. Agus Riyanto said he was unaware of any terrorism threat against banks and hotels in Surabaya, but promised that security would be increased.

The U.S. views Indonesia, the country with the highest population of Muslims, as a voice of moderation and important partner in countering Islamist militancy. Washington wants Jakarta to stop any flow of fighters from Indonesia to the Middle East and tighten controls on terrorist financing.

Indonesia has seen a spate of deadly attacks by Muslim militants, including the 2002 Bali bombings that killed 202 people, mostly foreign tourists. However, in recent years, smaller and less deadly strikes have been targeting mainly police and anti-terrorism forces.