JAKARTA, March 22 (Reuters) - No Indonesian airline will be closed after ratings of the carriers are announced on Thursday, the country's aviation chief said, amid pressure to improve air safety following a string of accidents in recent months.

A team set up by the government to evaluate transport safety following the disappearance of an Adam Air jet carrying 102 people in January has recommended that airlines found to have violated safety standards be shut down.

Budhi Muliawan Suyitno, the director general of civil aviation at the transport ministry, said 20 aviation companies had been put into three rating classes with the lowest batch for airlines that only meet minimal standards of safety.

The individual ratings were expected to be announced later on Thursday.

"All airlines are in those three ratings. The third rating means they have fulfilled the minimum standard of civil aviation safety but they need to do other things," he told reporters at parliament.

"If they are in the third rating, they will receive warnings. If they do not perform in three months, then we will suspend them" from operations, Suyitno said.

Revoking the airline's licences would be a final step.

On March 7, a Garuda Indonesia plane with 140 people on board overshot the runway in cultural capital Yogyakarta and burst into flames, killing 21 people including five Australians.

Investigators have said the national carrier's plane came in too fast to land but they still do not know why.

Air travel in Indonesia, a sprawling country of more than 17,000 islands, has grown substantially since the liberalisation of the airline industry in 1999 which triggered price wars among airlines.

The rapid growth raised questions over whether safety has been compromised and aviation infrastructure and personnel can cope with the huge increase.

Indonesia is also grappling with problems in other modes of transportation. There have been two serious ferry disasters in recent months killing hundreds of people, while rail accidents on an ageing system built during the Dutch colonial era occur frequently. ((Reporting by Telly Nathalia, writing by Achmad Sukarsono, editing by Jerry Norton; Reuters Messaging: achmad.sukarsono.reuters.com@reuters.net; +6221 384-6364))

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