Australia Wednesday warned that terror attacks may be imminent in the Philippine capital Manila, saying it had received credible evidence that violence was brewing.

Canberra issued an updated travel bulletin calling for Australian travellers to be extremely cautious but did not raise its warning level for the country and gave no indication of who could be planning potential attacks.

“Reliable reports indicate that terrorist attacks may be imminent in Manila, including places frequented by foreigners such as large shopping malls and convention centres,” the foreign affairs department said.

The advisory restated Australia’s advice against travelling to the southern island of Mindanao due to the “very high threat” of violence and kidnapping.

Warning of an imminent strike on the restive island it said several foreigners had been kidnapped on the nearby Sulu Archipelago and Zamboanga Peninsula. One man, a Japanese national, was still in captivity.

“We strongly advise you not to travel to mainland Mindanao, the Zamboanga Peninsula and the Sulu Archipelago regions of Mindanao … due to the very high threat of terrorist attack, including kidnapping and related counter-terrorism operations,” the department said.

“Credible information indicates terrorists may be in the advanced stages of planning attacks. Attacks may be imminent and could occur at any time, anywhere in Mindanao.”

Muslim rebels and bandits frequently carry out kidnappings for ransom in Zamboanga and other parts of the volatile southern Philippines’ Mindanao region.

The Abu Sayyaf, blamed for the worst terrorist attacks in the Philippines’ history, is the most infamous group that operates in Mindanao and is well-known for kidnapping foreigners as well as locals.