The United States signaled Friday its intent to eliminate its stockpile of anti-personnel landmines and eventually join a global treaty banning them, boosting efforts to rid the world of the weapons.

The high-profile announcement was made at a conference in Mozambique's capital Maputo aimed at ultimately ensuring no armed forces use anti-personnel mines by 2025.

The number of people killed or maimed by APLs fell in 2012, according to the global watchdog Landmine and Cluster Munition Monitor, but still reached 4,000. In many cases, the mines are leftovers from wars that ended decades earlier.

"The United States took the step of declaring it will not produce or otherwise acquire any anti-personnel landmines in the future, including to replace existing stockpiles as they expire," National Security Council spokeswoman Caitlin Hayden said in a statement.

In 2009, Washington said it was reviewing its position on landmines but -- along with rivals China and Russia -- has failed to sign the Ottawa Convention that bans the use of APLs and envisions their eventual elimination.

Nuclear powers India and Pakistan have also not signed up, nor has arch-foe Iran.

Long-standing critics of the US policy say Washington's rivals are waiting on the United States to move before they do likewise.

The White House gave no timeline as to when it might eventually sign the treaty, but Hayden said the US delegation in Maputo "made clear that we are diligently pursuing solutions that would be compliant with and ultimately allow the United States to accede to the Ottawa Convention."

"We are conducting a high fidelity modeling and simulation effort to ascertain how to mitigate the risks associated with the loss of APL," she said.

"Other aspects of our landmine policy remain under consideration."

- 'Out of the shadows' -

The United States has provided more than $2.3 billion in aid since 1993 in more than 90 countries for conventional weapons destruction programs, Hayden noted.

Since Mozambique hosted its first landmine conference in 1999, the number of state parties to the mine ban convention has more than tripled from 45 to 161, although key major powers remain on the sidelines.

The US stockpile is believed to consist of about nine million self-destruct anti-personnel mines, Human Rights Watch said, cautiously welcoming Washington's announcement.

"The US has finally come out of the shadows in indicating it intends to join the landmine treaty, and let's hope it will move ahead rapidly to come on board," said HRW arms director Steve Goose.

"This is an important acknowledgment that the treaty provides the best framework for achieving a world free of deadly anti-personnel mines."

Handicap International US executive director Elizabeth MacNairn welcomed the announcement but cautioned that the lack of a timeline meant Washington "runs the risk of allowing its landmine policy review to drift" beyond the end of President Barack Obama's time in office.

- 'Nonexistent problem' -

But the decision immediately came under fire from critics in Congress, where the Senate would need to ratify the treaty.

Howard "Buck" McKeon, the Republican chairman of the House Armed Services Committee, accused Obama of being more interested in playing politics than saving lives.

"His announcement today is perfect for a feel-good press release but bad for the security of our men and women in uniform.," McKeon said.

"It is truly an expensive solution in search of a nonexistent problem. Irresponsible landmine use by other countries has come at a high humanitarian price, but America isn't part of that problem."

Pentagon officials have in the past said that the United States needs landmines to defend South Korea against North Korea.

Pentagon spokesman Rear Admiral John Kirby said that both civilian and military leaders supported Obama's decision and would conduct simulation exercises with an aim to end the inventory of anti-personnel landmines.

The United States has an arsenal of some three million anti-personnel mines, which will deteriorate within 10 years, but does not have them deployed anywhere in the world, Kirby said.

State Department deputy spokeswoman Marie Harf said that the United States had studied ways to ensure South Korea's security, telling reporters: "This announcement does not in any way affect the defense of the Korean Peninsula."