Prime minister Manmohan Singh on Wednesday pressed for an early reform of the United Nations, particularly an expansion of the Security Council, noting it must be seen as an impartial, credible and effective world body.

In a statement before leaving for Frankfurt enroute to New York to attend the 66th Session of the UN General Assembly(UNGA), Singh also said efforts by India to promote international peace and security after it became a non- permanent member of the Security Council has enriched the policy making body's effectiveness.

"The United Nations must be seen as an impartial, credible and effective body. I will stress the need for early reform of this unique organization, particularly an expansion of its Security Council," he said.

India is seeking a permanent berth in the Security Council. It became a non-permanent member of this body in January this year after a gap of 19 years.

"Our efforts at promoting international peace and security and bringing to bear a developing country perspective have, I believe, enriched the Council's deliberations and enhanced its effectiveness," Singh said.

Noting that the UNGA is meeting this year at a time when the world is faced with multiple challenges, the prime minister said more than ever before, it is imperative for all countries to act in concert to address these challenges.

"This is the time for United Nations to resume its global leadership role," he added.

Making a mention of the challenges, Singh said the global economy is in the midst of an economic slowdown coupled with all its attendant problems, including inflationary pressures.

Terrorism and non-traditional threats to international security, such as piracy, are threatening states and the international political and social order, he noted.

He also said West Asia, North Africa and Gulf regions have seen major upheavals and there is uncertainty about the shape of things to come in this crucial part of the world in the period ahead. The Palestine question remains unresolved, he added.

Singh said he also looking forward to holding bilateral meetings with the presidents of Iran, South Sudan and Sri Lanka, and the prime ministers of Japan and Nepal.

Singh is being accompanied by external affairs minister S M Krishna, national security adviser Shivshankar Menon and foreign secretary Ranjan Mathai,

He would represent India at the high-level segment of the general assembly on Saturday when he is due to deliver his address.

The prime minister is attending the UNGA after a gap of two years.