Liberia's President Ellen Johnson Sirleaf said Thursday that Africa will face more conflict like her country's devastating civil war unless arms trade treaty negotiators produce a tough accord.

The Nobel Peace Prize winning president told envoys negotiating a deal that they had "a once in a lifetime opportunity to agree tough controls on the arms trade."

"The Liberian experience and other experiences in Africa and other parts of the world show that without such a treaty, armed violence and wars will continue to be fueled by irresponsible arms transfers," she said in a speech by video from Monrovia.

Internal wars between 1989 and 2003 left nearly 250,000 dead in Liberia.

"Let us make history in the next few days and change the world for the better," Johnson Sirleaf said.

She called for the treaty to cover light arms and munitions -- a contentious topic in the 10-day-old talks. The Liberian leader said the world had to avoid a repeat of the arms trafficking which fuelled the final battle for Monrovia in 2003.

On top of the deaths, Johnson Sirleaf said that conflict is costing Africa more than $18 billion a year, noting: "This is money our continent can ill afford to lose."

The arms trade talks are set to last until July 27 with the aim of agreeing a treaty on the trade in conventional weapons.

Negotiations are already struggling however with major exporters and importers seeking to weaken the scope of the accord, according to diplomats and pressure groups.

The United States wants munitions excluded while China does not small arms to be in the treaty, they say.

Meanwhile, the US representative at the talks, Donald Mahley, objected Thursday to the selection of Iran as one of 14 vice presidents of the UN conference.

"Iran's longstanding record of weapons proliferation, illicit nuclear activities, and gross human rights abuses properly disqualifies it from serving in any such position in the United Nations," Mahley said.

Accusing Iran of violating UN Security Council obligations by arming the Hezbollah group in Lebanon and the Syrian government, the envoy said "this selection makes a mockery of this conference's underlying purposes and undermines the credibility of the United Nations."