Keeping Southeast Asian waters safe will be a major benefit from closer co-operation between the Chinese and Thai navies, Virot Ali, Thai political commentator said.

Mr. Ali was speaking as Thailand was among the nations joining the celebration of the 70th anniversary of the founding of the Chinese People's Liberation Army Navy.

Warships from Thailand joined a huge naval parade, off the Chinese coast, alongside those of a dozen other countries in a multinational fleet.

China and Thailand have longstanding diplomatic and cultural relations and growing commercial links involving joint projects and investment.

Cooperation between the two navies is increasing, primarily to enhance joint capability in humanitarian roles.

"I think if China wants to become more active in the framework of ASEAN or in bilateral relationships with any country in Southeast Asia then Thailand would be the country they can relate with very easily and very closely at the beginning and then slowly they could expand and develop into a multilateral arrangement within the region," said Mr Ali, who is Associate Dean of International Affairs at Bangkok's Thammasat University

"We have to realize that China is expanding its capability through Belt and Road not only in a security or military dimension but economic as well, so by keeping the waters safe it's good for trade and it will be a win-win strategy for a lot of countries who are involved."

In a further sign of its close relationship, the Thai government is purchasing a submarine from China to bolster regional security.

Thailand will take the delivery of a Chinese Yuan-class vessel, with an option to buy two more.

The submarine, Thailand's first undersea capability for more than 60 years, will be used to combat people trafficking, piracy and illegal fishing in Thai waters and to contribute to regional maritime security.

Thailand was one of dozens of countries around the world which offered official congratulations to China to mark the anniversary and said it looks forward to developing even closer co-operation between the two country's naval fleets.

Mr Ali added: "The co-operation we have been seeing between the Chinese navy and Thailand has been very close since 2012 and I think this can progress into a very important relationship."

The Thai navy said it also stands ready to support China in non-military operations, such as casualty evacuation, providing help after natural disasters and in aid and relief missions.