Thailand is not participating in the US-initiated Trans-Pacific Partnership (TPP) free-trade negotiations, official here said on Friday.

The 17th round of TPP negotiations is due to begin in Peru on May 15. A web page designed by the Peruvian government to promote the event displays flags of countries and groups that are "full participants" or "discussing entry" and "negotiating a part" in the talks.

Thailand's national flag is placed in the first category.

The Bangkok Post, an English-language daily paper in Thailand on Friday dismissed the arrangement as "misleading," saying the kingdom has been "standoffish" about TPP from the beginning.

"You can say we are officially still thinking about whether to participate in the TPP negotiations," a foreign ministry official was quoted as saying.

TPP, a pet project of US President Barack Obama, is a free trade agreement which aims to further liberalize the economies of the Asia-Pacific region. It is widely seen as a US strategy to counter China's economic clout in the region.

During his official visit to Bangkok last November, Obama invited Thailand to join the TPP negotiations. But many Thai businesses are concerned that while seeking to impose new and stronger restrictions on intellectual property, human rights and labor rules, TPP would pose threat to the healthy development and integrity of Thai economy.

With Japan officially joining the negotiations earlier this week, TPP has expanded to include 12 countries.