BANGKOK - Prime Minister Mahathir Mohamed arrived in the northern Thai city of Chiang Mai today for a three-day official visit focusing on economic cooperation and security, officials said.

Mahathir was officially welcomed at Chiang Mai's military airport by Thai Prime Minister Thaksin Shinawatra, an airport official said.

It is the first time the Thaksin administration has hosted a visit by the long-serving Malaysian prime minister. Thaksin paid an official visit to Kuala Lumpur in April 2001.

Mahathir, who has caused a stir in Malaysia with his resignation announcement, is scheduled to visit village projects in Chiang Mai before heading to Bangkok Saturday.

He will hold bilateral talks with Thaksin in the capital before being granted a royal audience with Thailand's Queen Sirikit at Chitralada Palace.

King Bhumibol Adulyadej is currently recovering from a hernia operation.

Thaksin told reporters today he would reassure Mahathir that a controversial billion-dollar gas pipeline project linking southern Thailand with an offshore field being jointly developed with Malaysia would go ahead.

"The government wants to reaffirm that the project will not cause anyone hardship, and we are confident that the environmental impact will be controlled," he said.

The pipeline was originally due to begin operation this year, but the plan has been stalled by strong opposition from Thai environmental groups, who were planning protests during Mahathir's visit, they said in a statement.

Security problems

The leaders would also discuss security problems along their common border, Thaksin said.

Some 12 police officers have been killed in recent months in the south of Thailand, and although authorities have not pinpointed its catalyst, Thaksin has suggested that the dual citizenship of known troublemakers in the region could be revoked either by Thailand or Malaysia.

Government spokesman Yongyuth Tiyapairat said Thaksin would also raise the issue of extending official working hours at border checkpoints, to increase trade and tourism.

Economic issues are also on the agenda, Yongyuth said.

Malaysia is Thailand's second largest trading partner within the Asean grouping of nations, after Singapore, with two-way trade amounting to RM22.4 billion in 2001.

Mahathir is scheduled to return to Kuala Lumpur on Sunday morning. AFP