"We need to modernise the UN Security Council. The UNSC ought to include India as a permanent member, there is no doubt about that," Cameron said during a 40-minute interaction with students of the Indian Institute of Management-Calcutta here.

"The UN is not perfect but it is good to have such bodies in the world. We must back the UN," Cameron added.

The Prime Minister said the Security Council demonstrates "political will", and stressed on the need of the global panel to show the will on "deciding to act and deciding on taking a stance".

He said the UN took a stand on Libya, "and took a view" and allowed the ushering in of changes.

He termed the Commonwealth as a "club", and a "good organisation" to have.

"It is a meeting place where we pat each other on their back when we get thingsright and point a bit of fingers when we get wrong".

"In an ideal world, I would see it get tougher on human rights issues," said Cameron.

Cameron, who flew to Sri Lanka to attend the Commonwealth Heads of Government Meet, said the members will get an opportunity in Colombo to "talk about issues like climate change, how we can make the UN a driving force against poverty".

The British Prime Minister said he welcomed the Arab Spring, but also recognised there would be setbacks.

Describing the alleged use of chemical weapons by the Syrian government on its opponents as "dreadful", Cameron pointed out that the strong stance taken by some countries forced Damascus to remove and destroy such weapons.