The United States says a review of its landmines policy is ongoing - a day after it had announced Washington would not sign an international convention that bans the weapons.

A State Department spokesman Ian Kelly said Tuesday the United States would not be able to meet its national defense needs if it signed the global treaty.

But in a statement Wednesday, Kelly said the Obama administration is still looking at its overall policy and while the review continues the current policy will stay in place.

Kelly said Washington still plans to send an inter-agency delegation of humanitarian mine experts to Cartagena, Colombia next week to observe a review conference on the decade-old Mine Ban Treaty.

More than 150 countries have agreed to the treaty's provisions to end the production, use, stockpiling and trade in mines.

Kelly said the United States is the world's single largest financial supporter of humanitarian mine action, having provided more than $1.5 billion since 1993 to support mine clearance and destruction of conventional weapons.

The administration of former President Bill Clinton refused to sign the treaty but set a target of 2006 for renouncing the use of landmines.

In 2004, former President George W. Bush's administration revised the U.S. policy and said it would ban mines without self-destruct features after 2010.  But, it said it would impose no limits on so-called "smart" mines which have timing devices to automatically de-fuse explosives within hours or days.

The International Campaign to Ban Landmines says the devices are known to have caused nearly 5,200 casualties last year.

Some information for this report was provided by AP and Reuters.