New PM says Britain not turning inward

May, who took office in July after the "Brexit" vote led her predecessor David Cameron to resign, said that Britain "has always been an outward-facing, global partner" in international affairs.

"And that is how we will remain. For when the British people voted to leave the EU, they did not vote to turn inwards or walk away from any of our partners in the world," May said in an address to the UN General Assembly.

May said that Britain, one of five veto-wielding permanent members of the UN Security Council, would remain a player on major issues including fighting poverty, terrorism and climate change.

She pledged a particular focus on preventing human trafficking, saying that criminals had created a modern form of slavery.

"We need to be smarter and even more coordinated than the criminal gangs in our efforts to stop them," she said.

May said that she committed to Nigeria the first five million pounds ($6.5 million) from a new fund that aims to help stop human trafficking from countries to Britain.

The United Nations estimates that nearly 21 million people around the world are victims of forced labor, with more than half of them women and girls.

In line with her remarks a day earlier at a UN summit on refugees, May devoted much of her address to urging a tougher stance amid the massive flow of migrants into the West.

She called for more distinction between refugees fleeing persecution and economic migrants. She said asylum seekers should always apply in the first safe country where they step foot -- meaning Turkey, Lebanon and Jordan for most fleeing war-torn Syria.