The world's nuclear power generation capacity grew again in 2012 after a drop in 2011 in the wake of the Fukushima disaster, according to a draft new UN atomic agency report seen by AFP Tuesday.

"The Fukushima Daiichi accident (in Japan in March 2011) is expected to slow or delay the growth of nuclear power, but not reverse it," the International Atomic Energy Agency report said.

At the end of 2012, 437 nuclear power reactors were operating worldwide, two more than in 2011, with three new ones connected to the grid, two back on line after repairs and three permanently shut down, it said.

In 2011, after what was the world's worst nuclear accident in 25 years, 13 reactors were permanently switched off, including eight in Germany and four in Japan, although there were seven new grid connections.

In 2012 nuclear power's total electricity generation capacity -- as opposed to total actual production -- rose 3.7 gigawatts to 372.5 gigawatts, compared to a drop of seven gigawatts in 2011, the IAEA said.

The IAEA was created in 1957 and one of its main roles is to promote the peaceful uses of atomic technology, and has therefore been criticised by ecologists for lobbying for the nuclear industry.

In the new report, the IAEA gave no figure for actual electricity production and its generation capacity estimate includes all of Japan's 50 reactors, even though only two are currently operating.

On Monday, the head of French nuclear group Areva, a major supplier to Japan, said half a dozen reactors would reopen before the end of the year and that most of the country's nuclear plants would eventually come back online.

Japan's nuclear watchdog on Tuesday said that nothing had been decided yet.

Construction work started on seven new reactors in 2012, four of them in China and one each in South Korea, Russia and the United Arab Emirates, added the report, called the 2013 Nuclear Technology Review.

"Although higher than in 2011 (when work began on just four reactors), this is significantly fewer than in 2010, when the steady increase since 2003 reached its peak with 16 new construction starts," the report said.

On the other hand, only three reactors were declared permanently shut down in 2012 -- one in Canada and two in Britain more than 40 years old -- and in total 67 reactors are being built, 47 of them in Asia.

The IAEA also noted that countries were looking to extend the lifetime of nuclear plants, as well as "growing interest" in small and medium-sized reactors, which are cheaper to build.

Overall, the IAEA forecasts growth of anywhere between 23 percent and 100 percent in nuclear power capacity by 2030.