The announcement came more than 18 hours after flight MH370 slipped off radar screens somewhere between Malaysia’s east coast and southern Vietnam, triggering an international search effort.
“Two of our aircraft sighted two oil slicks around 15 to 20 kilometres (10-12 miles) long, running parallel, around 500 metres apart from each other,” the army’s deputy chief-of-staff, Vo Van Tuan, told state-run VTV.
“We are not certain where these two oil slicks may have come from so we have sent Vietnamese ships to the area.”
Air search operations were halted at nightfall, though ships continued searching, the airline said, adding that no trace of the passenger plane had been found as of late Saturday.
“I think the two oil slicks are very likely linked to the missing plane,” Vice-Admiral Ngo Van Phat, who is helping to direct the search mission, told AFP late Saturday.
“However, we have to check carefully once our rescue boats get access to the area,” he said, adding the boats were around an hour from the site of the slicks and were expected to search a wide expanse of sea in darkness.
The twin-engine jet had been flying from Kuala Lumpur to Beijing, where anguished relatives were Saturday evening still desperately waiting for news.
The plane had 227 passengers – including 153 Chinese nationals – and 12 crew, according to the airline.
An Austrian and an Italian thought to have been on the plane both had had their passports stolen and are safe, officials and family members said.
Italian Luigi Maraldi, 37, was on the passenger list, but phoned home from Thailand to let his family know he was safe – and before his father had seen the news.
Malaysia Airlines also contacted the Austrian foreign ministry, saying that the name of an Austrian was on the passenger list of the plane, a spokesman for the ministry said.
Austrian authorities confirmed the man was safe in Austria.