The government issued a stronger official warning Friday on Indonesia, urging people to refrain from traveling there until the situation stabilizes, Chief Cabinet Secretary Kanezo Muraoka said.

The warning, a level three on the government's five-tier scale, was issued after a level-four warning Thursday advised people to refrain from sightseeing and other nonessential trips to the country.

"We cannot make any predictions as to Indonesia," Muraoka said. "We should keep watching over the situation." Earlier in the day, the government held an emergency Cabinet meeting to discuss measures for protecting 20,000 Japanese in the riot-plagued country.

"We have to deal with the situation with the worst-case scenario in mind," Foreign Minister Keizo Obuchi said. "We have grave concerns about the situation and cannot predict what will happen from here on."

But, he added, "We have heard that the areas where many Japanese live are calm and that no Japanese nationals have been injured so far."

Defense Agency chief Fumio Kyuma told reporters that the agency will make necessary preparations to send military aircraft to evacuate Japanese people if the agency is asked to do so by the Foreign Ministry.

"We will prepare for a possible request from the Foreign Ministry to conduct an evacuation," Kyuma said, adding that the ministry should ask countries that may be on flight routes taken by Self-Defense Forces planes for permission to use their airspace.

However, the defense chief indicated the situation is not yet serious enough to conduct an evacuation.

"The situation seems to be different from when the government dispatched (last July) C-130 (Hercules transport planes) to Thailand to prepare for the possible evacuation of Japanese nationals from Cambodia," Kyuma said.