Japan issued a warning to its nationals on Monday about a possible attack in six Southeast Asian countries, encouraging them to avoid holy places.

According to the Japanese Foreign Ministry, "there are increasing hazards such as suicide bombings."

This unexpected warning is issued to Japanese nationals in Indonesia, the Philippines, Singapore, Malaysia, Thailand, and Myanmar.

None of these countries are regarded Japan's rivals or enemies, and relations between Tokyo and the majority of them are reasonably stable.

Japan has launched a successful diplomatic campaign in the Southeast Asian region to oppose China's comparable assertive strategy through economic cooperation, alternative connectivity projects, and security engagements throughout the last decades.

As a result, numerous of these countries were taken aback by Monday's warning.

According to the Japanese Embassy in Manila, the Japanese government has received information regarding a probable terror strike in six Southeast Asian countries.

"We confirm that the Japanese government has received information about a possible terror attack, but we cannot give any detailed background at the moment," the Embassy said.

"We issued a warning to alert Japanese people residing in some Southeast Asian countries, but we cannot disclose the source," it added.

The Department of Foreign Affairs said that it was not officially informed on the matter.

"The DFA has not been officially informed about this matter. Travel alerts for a country's citizens are usually not officially notified to other countries, however, this type of information may have been shared among intelligence agencies," the DFA said.