The eleven countries that participate in a trans-Pacific free trade agreement said Saturday they will seek to expand membership in a quest to form a stronger united front against the rise of protectionism, amid an ongoing tariff war between China and the United States.

The trade pact is "open to all economies" that can meet its high-standard rules, delegates from the member countries said in a joint statement after attending a meeting in Tokyo, as the list of potential newcomers includes Thailand, Britain and Taiwan.

The existing member countries, including Australia, Japan and Singapore, held their first ministerial meeting since the pact known as the Comprehensive and Progressive Agreement for Trans-Pacific Partnership, took effect on Dec. 30 without the United States.

"It is our hope to see participation by as many countries and regions as possible. That includes the United States," Toshimitsu Motegi, Japan's minister in charge of the trade pact, said at a press conference.

The accord, covering around 13 percent of the world economy, is designed to cut tariffs on agricultural and industrial products, ease investment restrictions and enhance intellectual property protection.

"Amid growing concerns over recent trends toward protectionism, ministers shared the view that it is of paramount importance to maintain and further strengthen the principles of an effective, open, inclusive and rules-based trading system," the statement said.

At the inaugural meeting of the trade bloc's decision-making panel, the current members decided on procedures for accepting new members and the rules for settling disputes.

It was also agreed that when a country aspires to join the trade framework, the panel will review the negotiations and make a decision as to whether the country can join.

Japan held a ceremony at the prime minister's office at which the delegates and business leaders celebrated the CPTPP coming into effect.

But despite the joint push by the 11 countries for an expanded CPTPP, the outlook remains uncertain following the defeat in parliament of the British government's plan to exit the European Union as well as a planned general election in Thailand, analysts said.

Still, the entry into force of the CPTPP marked a critical milestone for the 11 countries that sought to save its older version, simply called the TPP, from collapse after U.S. President Donald Trump pulled the world's largest economy out of it.

Trump's pursuit of his "America First" agenda and bilateral deals to fix what he sees as imbalanced trade have rattled financial markets and sparked worries about the global economy.

Canada and Mexico have renegotiated the North American Free Trade Agreement targeted by Trump.

Canada's trade minister Jim Carr, speaking at the joint press conference, said free trade agreements are "bridges" built by governments, but they need to be crossed by investment, goods and services so people can feel their benefits.

Joining hands to pursue a multilateral approach to trade, Australia, Canada, Japan, Mexico, New Zealand and Singapore became the first six countries to end their domestic processes to ratify the pact, signed in March last year.

The CPTPP became effective for Vietnam last Monday, while Brunei, Chile, Malaysia and Peru have yet to end their domestic procedures to ratify it.

Appearing at the outset of the ministerial meeting, Japanese Prime Minister Shinzo Abe spoke of the need to make the pact effective for all 11 members "as soon as possible" as confidence in the global trade system has been "greatly shaken."

Japan has been promoting multilateral free trade arrangements while it awaits the start later this year of bilateral trade talks with the United States. Another free trade agreement with the European Union is set to take effect on Feb. 1.

"Japan will aim to expand the free, fair, and rules-based economic area," Abe said. "As Group of 20 chair this year, we will spare no effort to strengthen the international trade system, including reform of the World Trade Organization."