Taiwan's leader said he is in favour of joining the Asian Infrastructure Investment Bank in comments published Friday, making it the latest economy to express interest in joining the Beijing-backed institution.

It was not immediately clear if the island could actually join the AIIB, as the mainland has long opposed allowing Taiwan to join any international organisations that confer sovereignty upon it.

President Ma Ying-jeou's remarks came after the bank, which the United States has opposed, has attracted several potential new members this month, including staunch American allies Britain and South Korea.

"I am in favour of joining (AIIB) in principle," Ma told the Taipei-based China Times newspaper.

"We should not stay on the sidelines. (We) should actively participate in it."

He explicitly linked potential membership in the AIIB to Taiwan's bids to join other proposed multinational free-trade blocs, such as the Trans-Pacific Partnership and the Regional Comprehensive Economic Partnership (RCEP).

"We hope to participate in regional economic integration and many countries that will benefit from AIIB are members of RCEP or are in the Asia-Pacific region," he said.

It was not immediately clear whether Beijing would allow any application by Taiwan, which it regards as part of its territory awaiting reunification.

- 'Welcome all countries' -

This week Beijing's vice finance minister, Shi Yaobin, said it "welcomes all countries" to join the bank, which it has touted as a tool for financing regional development alongside other lenders such as the World Bank and the Japan-led Asian Development Bank.

Beijing's foreign ministry referred enquiries by AFP to the finance ministry, which did not immediately respond. Calls to the Taiwan Liaison Office were not answered.

Ma acknowledged the hurdle of statehood in the interview, the newspaper said, but claimed those obstacles could be discussed when former vice president Vincent Siew and Chinese President Xi Jinping meet Saturday at the Boao Forum, an annual gathering of political and economic leaders.

Taiwan's involvement in international agreements is often curtailed by China, which considers it part of its territory awaiting reunification. They split in 1949 at the end of a civil war.

It has, however, joined international organisations in the past under different names. The International Olympic Committee refers to it as "Chinese Taipei", and it is known as the Separate Customs Territory of Taiwan, Penghu, Kinmen and Matsu at the World Trade Organization.

Ties have improved rapidly between China and Taiwan since Ma and his Beijing-friendly Kuomintang (KMT) party came to power in 2008.

The KMT, however, is tipped to lose power in next year's presidential polls to the China-sceptic Democratic Progressive Party (DPP).

The opposition grouping expressed reservations over the AIIB on Friday. Spokesman Cheng Yun-peng said the government "should evaluate why is it necessary and ensure that Taiwan will join with an identity that won't hurt our dignity or affect the overall national development".

Britain, Germany, France and Italy have all said they intend to join the $50 billion bank, despite scepticism about the AIIB in Washington and Tokyo.

South Korea on Thursday became the latest country with close ties to the US to say it would also seek membership.