New Delhi, Sep 21 (IANS): Prime Minister Manmohan Singh Wednesday called upon all nations to address the multiple challenges the world is facing today, such as economic slowdown, terrorism and unrest in West Asia and North Africa, ahead of his visit to the UN.

"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," the prime minister said in a statement ahead of his six-day visit from Wednesday.

"During my visit, I look forward to holding bilateral meetings with the presidents of Iran, South Sudan and Sri Lanka, and the prime ministers of Japan and Nepal," said the prime minister, off to attend the 66th Session of the UN General Assembly.

His delegation includes External Affairs Minister S.M. Krishna, his Principal Secretary T.K.A. Nair, National Security Advisor Shiv Shankar Menon and Foreign Secretary Ranjan Mathai.

"The UN General Assembly is meeting this year at a time when the world is faced with multiple challenges. The global economy is in the midst of an economic slowdown coupled with all its attendant problems, including inflationary pressures," the prime minister 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 said.

He also said terrorism and non-traditional threats to international security, such as piracy, were threatening states and the international political and social order and called for collective action to address all these issues.

According to the prime minister, his latest visit to the UN also comes against the backdrop of India once again becoming a non-permanent member of the Security Council, since 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," he said.

"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."

The current UN session started Sep 13. This year, the general debate and addresses by the heads of delegation is scheduled from Set 21-Sep 30. The Indian prime minister is scheduled to address the General Debate in the morning of Sep 24.