Britain intends to build a new generation of nuclear power plants to replace its decades-old reactors, partly as a strategy for meeting its goals to reduce carbon emissions, Foreign Minister William Hague said Monday.

"We will have, from the 2020s onward, an expanding nuclear power sector," Hague told an audience at the Council on Foreign Relations.

Hague's main topic was the urgency of an international accord to address climate change — which he said, along with the proliferation of nuclear weapons, is among the key crises facing the world in the 21st century.

Partly as a strategic decision to lower its carbon emissions and reliance on imported energy, "We have decided in Britain to build a new generation of nuclear power stations."

"I really see no alternative to that except excessive dependence on oil and gas, and imported liquefied natural gas," Hague said.

"So after quite a long gap in which we haven't built any nuclear power plants, we are opening the door to doing so again. They have to justify themselves economically," and will mainly be built on the sites of existing reactors, Hague said. He didn't say how many would be built.

Most of Britain's existing nuclear power stations are due to be retired over the next 15 years. Nuclear power generates about a fifth of Britain's energy needs.