Ukraine remembers Chernobyl blast
President Yushchenko joined mourners at the night-time vigil
Ukraine is holding a series of events to commemorate the 20th anniversary of the world's worst nuclear disaster at the Chernobyl power plant.
The blast was marked by tolling bells and a minute's silence at 0123 local time (2223 GMT on Tuesday) - when the alarm was set off on 26 April 1986.
The explosion tore off the plant's roof, spewing radioactive fallout over swathes of the then-USSR and Europe.
President Viktor Yushchenko will visit the site later in the day.
He will meet some of the people who worked at the plant and those who risked their lives to deal with the accident.
A monument to victims is due to be unveiled, and the country's parliament is holding a special hearing into the disaster.
In neighbouring Belarus, also badly affected by fallout, opposition groups are expected to hold a rally in the capital Minsk to protest against government attempts to rehabilitate contaminated areas.
'Ask for forgiveness'
At evening ceremonies, hundreds of mourners, each carrying a single red carnation and flickering candles, gathered for the outdoor Orthodox Christian service at the church in Kiev.
President Yushchenko laid a wreath to remember those who were sent to deal with the accident and to the many who have since been affected.
A sarcophagus was erected over the ruins of Chernobyl's fourth reactor
At precisely 0123, the church bells tolled 20 times.
A similar ceremony got under way an hour earlier, to coincide with 0123 Moscow time, in Slavutych, the town built to house the Chernobyl plant workers displaced by the accident.
To the sound of bells tolling and alarm sirens blaring, mourners laid flowers and candles at a monument dedicated to those who died in the immediate aftermath of the accident.
"I knew all of these people," a tearful Mykola Ryabushkin told the AFP news agency, pointing to the portraits hanging on the monument.
The 59-year-old had been working as an operator at the plant when the explosion happened.
"I look at them and I want to ask them for forgiveness," he said. "Maybe we're all to blame for letting this accident happen."
Disputed death toll
The accident happened at one of four reactors at the Chernobyl nuclear power plant, 110km (70 miles) north of the capital, Kiev.
Throughout most of the following day the Soviet authorities refused to admit anything out of the ordinary had occurred.
It was only two weeks after the explosion, when radiation releases had tailed off, that the first Soviet official gave a frank account, speaking of the "possibility of a catastrophe".
Official UN figures predicted up to 9,000 Chernobyl-related cancer deaths. But a Greenpeace report released last week estimated a figure of 93,000. Greenpeace said other illnesses could bring the toll up to 200,000.
A restricted area with a radius of 30km (19 miles) remains in force around the destroyed nuclear reactor which is encased in concrete.
http://news.bbc.co.uk/2/hi/europe/4944898.stm