SINGAPORE - Singapore has offered to deploy more vessels to help in the search and locate efforts of missing AirAsia Indonesia flight QZ8501.

The Republic has offered Indonesia a few ships that can assist in the operations - a frigate, a landing ship tank (LST), a corvette, and the MV Swift Rescue, said Defence Minister Ng Eng Hen in a Facebook post on Sunday night.

"I've spoken again to Indonesian Defence Minister Ryamizard Ryacudu and have offered the Indonesians a few ships that can assist in the search-and-locate mission - A frigate, an LST, a corvette, and the MV Swift Rescue. These vessels are already on standby," he wrote.

The Singapore Rescue Coordination Centre, managed by the Civil Aviation Authority of Singapore (CAAS) and supported by various agencies, including the Republic of Singapore Air Force and the Republic of Singapore Navy, offered assistance to the Indonesian Search and Rescue Agency, at 9.30am on Sunday. The Indonesian authorities accepted the offer at 2.30pm, requesting for one C130 plane.

A Republic of Singapore Air Force C130 plane took off at around 5pm and reached the search area at around 630pm. It carried out search and locate operations for two hours, said the Ministry of Defence. The plane left the search area after the Indonesian authorities called off the search for the day.

In an update on Sunday evening, CAAS said two more planes will set off from Singapore early on Monday morning to continue with the search.

CAAS added that it will also be sending an officer to the Indonesian National Search and Rescue Agency in Jakarta to assist in the coordination with the Indonesian authorities on the search operations. The Singapore Ministry of Transport's Air Accident Investigation Bureau has also offered the Indonesian authorities two teams of specialists and two sets of underwater locator beacon detectors to assist with the search.

Singapore leaders have said the Republic is ready to pitch in if Indonesia needs help.

Prime Minister Lee Hsien Loong wrote on his Facebook page on Sunday: "Sorry to learn that an AirAsia aircraft from Surabaya to Singapore has gone missing. We don't have many details yet, but have offered our help to the Indonesian authorities. Our thoughts are with the passengers and their families."

He added: "Called President Joko Widodo to express concern and offer help. Two RSAF C-130 search and locate aircrafts are on standby, ready to go. Our ministers are following up."

Deputy Prime Minister Teo Chee Hean said he has visited the next-of-kin of passengers waiting at Changi Airport. "Just landed at Changi and learned about missing AirAsia flight. Visited the families who are waiting for their loved ones at NOK centre. Assured them that we will continue to update and assist them," he wrote in a Facebook post.

The plane was travelling from Surabaya to Singapore on Sunday morning. It has 155 passengers - 149 Indonesians, one Singaporean, one British, one Malaysian and three Koreans - according to Indonesia's Transport Ministry. Also on board were two pilots and five cabin crew.

Transport Minister Lui Tuck Yew, in a Facepost post, said: "Our thoughts and prayers are with the crew, passengers and families of the missing Indonesia AirAsia flight QZ8501. I understand that the Indonesian authorities have activated search and rescue operations. I spoke to my counterpart in Indonesia and offered our C130s to support the SAR. Our relevant agencies have been activated and are ready to provide assistance at short notice."