|Activists light candles to display a nuclear radiation warning sign during an anti-nuclear rally in Vienna [Reuters]
Russian and Ukrainian leaders have marked the 25th anniversary of the Chernobyl nuclear disaster at a time when fears over atomic energy are running high.
Dmitry Medvedev, the Russian president, said that he wanted new world rules covering safety at nuclear plants, as he visited the site of the 1986 catastrophe on Tuesday.
For his part, Viktor Yanukovych, the Ukrainian president, paid tribute to those who lost their lives in the Chernobyl accident, which saw a nuclear explosion spew radiation into the atmosphere. Higher-than-normal levels of radiation persist in the area to this day.
The explosion released about 400 times more radiation than the US atomic bomb dropped over Hiroshima. Hundreds of thousands were sickened and once-pristine forests and farmland still remain contaminated.
Al Jazeera's Neave Barker, reporting from inside the exclusion zone at Chernobyl, said there was a mixture of sadness and hope in the country.
"Last week a major international conference was held in Kiev, attended by dozens of countries, many pledging billions of dollars in aid to complete a final protective covering over the Chernobyl reactor number four that experts say will provide an extra 100 years of protection," he said.
The UN's World Health Organisation said at the conference that among the 600,000 people most heavily exposed to the radiation, 4,000 more cancer deaths than average are expected to be eventually found.
"We spoke to one girl who was born three years after the disaster but because of her mother's exposure to the radiation she's ended up with serious illnesses. So this is an accident that is still being felt to this day," our correspondent said.
'Tell the truth'
In his remarks on Tuesday, Medvedev said Chernobyl had offered the lesson to states that they must tell people the truth about nuclear accidents.
"We must give absolutely accurate information about what is happening," he said. "Today, I sent proposals to [world] leaders ... aimed at guaranteeing the necessary development of nuclear energy in the world while preventing at the same time catastrophic global consequences [of accidents]."
The anniversary comes amid ongoing concerns about the nuclear crisis in Japan, triggered by an earthquake and tsunami in March.
Yanukovych said: "We are marking a tragic date. Twenty five years have passed and we have understood that nuclear accidents have colossal consequences for the population.
"The world has understood that such catastrophes cannot be fought by one country on its own."
Earlier, black-clad Orthodox priests sang solemn hymns, Ukrainians lit thin wax candles and a bell tolled 25 times for the number of years that have passed since the Chernobyl disaster.
Russian Orthodox Patriarch Kirill led the night time service early on Tuesday near a monument to firefighters and cleanup workers who died soon after the accident from acute radiation poisoning.
"The world had not known a catastrophe in peaceful times that could be compared to what happened in Chernobyl,'' said Kirill, who was accompanied by Mykola Azarov, Ukraine's prime minister, and other officials.
"It's hard to say how this catastrophe would have ended if it hadn't been for the people, including those whose names we have just remembered in prayer," he said in an emotional tribute to the workers sent to the
Chernobyl plant immediately after one of its reactors exploded to try to contain the contamination.
'Lives turned around'
Tuesday's service commemorated the time of the Chernobyl blast on April 26, 1986. The explosion spewed a cloud of radioactive fallout over much of Europe and forced hundreds of thousands from their homes in the most heavily hit areas in Ukraine, Belarus and western Russia.
Several hundred Ukrainians, mostly widows of plant workers and those sent in to deal with the disaster, came to the service to pay their respects to their loved ones and colleagues. Teary-eyed, they lit candles, stood in silence and crossed themselves to the sound of Orthodox chants.
"Our lives turned around 360 degrees,'' Larisa Demchenko, 64, said. She and her husband both worked at the plant, and he died nine years ago from cancer linked to Chernobyl radiation.
"It was a wonderful town, a wonderful job, wonderful people. It was our youth. Then it all collapsed," she said.
Russia, Ukraine and Belarus have cut the benefits packages for sickened clean-up workers in recent years, and many workers complained directly to Medvedev as he handed them awards for their work at a ceremony on Monday in Moscow.
Officials in Bryansk, the Russian region most contaminated by the disaster, have failed to make necessary repairs at the local cancer hospital, Leonid Kletsov, a worker, told Medvedev.
"It's the only place of rest for us," he said. "Officials promised to renovate it, but these promises are still promises."