Singapore welcomes Japan as a participant in the Trans-Pacific Partnership (TPP) negotiations, the government said on Sunday.

"We are confident that Japan will be a valuable partner in the development of a high quality agreement to spur economic growth across the Asia-Pacific region," said a joint statement by the Ministry of Foreign Affairs and the Ministry of Trade and Industry.

It said Singapore has consistently and strongly expressed support for Japan's early participation in the TPP and pointed out that Japan has long played a crucial role in the development of the Asia Pacfic and thus maintaining its stability.

"As the world's third largest economy, Japan's inclusion has further raised the strategic and economic significance of the TPP and reinforced the agreement's strategic vision of advancing regional economic integration and promoting regional development and stability.

"Japan's membership in the TPP will also encourage Japan's domestic growth and help its overall economic revitalisation," the statement said.

With Japan's inclusion, the TPP's membership has expanded to 12 countries representing nearly 40 per cent of the global economy and one-third of world trade.

The TPP is envisioned as an inclusive agreement that will lead to an eventual Free Trade Area of the Asia-Pacific.

"Singapore welcomes all countries in the region that will contribute to the TPP's objective of advancing regional economic integration," the statement added.