UNITED NATIONS - US President Barack Obama vowed Tuesday that NATO mission will continue so long as the Libyan people are being threatened.

Addressing a high-level meeting on Libya at the United Nations, also known as the Friends of Libya meeting, Obama called on loyalists of Libyan leader Muammar Gaddafi to lay down their arms. He called Libya "a lesson in what the international community can achieve when we stand together as one."

"I said at the beginning that we cannot and should not intervene every time there's an injustice in the world," he said. "Yet it's also true that at times the world could have and should have summoned the will to prevent the killing of innocents on a horrific scale."

The high-level international and multilateral meeting on Libya hosted by United Nations Secretary General Ban Ki-moon marks the start of the process of reconstruction and nation-building in Libya.

The UN chief called it "a historical day" for Libya, pledging UN support for the North African nation "in every way we can" in helping it meet the "large challenges" ahead.

Musta Abdel Jalil, chairman of the Transitional National Council (NTC) of Libya, pledged a fair trial for those accused of the Gaddafi regime.

Last Friday, the UN Security Council unanimously adopted a resolution to ease sanctions on Libya over assets and arms, and set up a UN mission to help restore public security as well as initiate economic recovery in the nation.

Hours earlier, the UN General Assembly approved NTC as the legitimate holder of the country's UN seat.