Ninety-three countries have signed a landmark treaty banning cluster bombs, seen as one of the biggest international humanitarian agreements clinched in the past decade, host country Norway said Thursday.

"We are on track," Norway's deputy minister of foreign affairs, Raymond Johansen, said at the end of the two-day signing ceremony in Oslo.

The Convention on Cluster Munitions (CCM), an umbrella organisation grouping some 300 humanitarian aid groups, said four or five additional countries may sign the text on Thursday.

The treaty was also to be sent to the United Nations in New York, where other countries will be able to sign it.

Major arms producers such as China, Russia and the United States have however refused to sign the treaty, unlike most European countries.

Afghanistan, Laos and Lebanon, three countries heavily affected by cluster bombs, also put their names to the document. Iraq has meanwhile said it would sign "as soon as possible."

The ban outlaws the use, production, transfer and stockpiling of cluster munitions, and requires signatories to assist victims of the weapons.

"This is the biggest humanitarian treaty of the last decade," Richard Moyes of the CMC said.

Dropped from warplanes or fired from artillery guns, cluster bombs explode in mid-air to randomly scatter hundreds of bomblets, which can be just eight centimetres (three inches) big.

Many bomblets fail to explode can kill and maim long after a conflict ends. More than a quarter of the victims are children who mistake the bomblets for toys or tin cans.

When the treaty was hammered out in negotiations in May in Dublin, it was agreed upon by 107 countries. Organisers attributed the difference between that number and the 93 that have signed the document so far to bureaucratic reasons.

The treaty must be ratified by at least 30 countries before it can go into effect. Norway, which played a key role in obtaining the ban, has already launched the ratification process, as have Ireland, Sierre Leone and the Holy See.