King Maha Vajiralongkorn, who has rarely made overseas state visits since he ascended the throne nine years ago, is in Beijing with his wife Queen Suthida for his first official visit to China.

Describing the two countries as like "family", Xi told the royals China would "strengthen strategic alignment" with the Southeast Asian country, according to state broadcaster CCTV.

He said cooperation would be expanded on a China-Thailand railway link as well as in emerging fields like AI, aerospace and the digital economy.

"King Vajiralongkorn's choice of China as his first major country for a state visit... fully demonstrates the high importance he attaches to China-Thailand relations", Xi said according to CCTV.

Thailand was a key ally of the United States during the Cold War, but China is now the country's largest trading partner and ties between Bangkok and Beijing have warmed in recent years.

The two countries have recently stepped up a joint crackdown on telecommunications fraud and illegal gambling gangs that operate in border areas, mostly in Myanmar, and often target Chinese nationals.

On Wednesday, Thailand extradited Chinese national She Zhijiang, who is allegedly linked to a lucrative scam hub in Myanmar.

He had been in Thai custody since 2022.

China also pushed for a ceasefire between Thailand and Cambodia, a close partner of Beijing, after border clashes in the summer caused dozens of deaths.

That truce has proved fragile, with Thailand on Monday pausing its implementation after claiming a blast from a newly laid landmine had wounded four of its soldiers.

The two sides have subsequently traded accusations of fresh clashes along their border.