CHORNOBYL, April 26 - Ukraine marked the 20th anniversary of the Chornobyl disaster Wednesday with pealing bells, candlelit ceremonies and parliamentary debates about how much the country still does not know.

Dozens gathered in the town of Chornobyl, 18 kilometers from the plant, for reunions with old friends, and parliament opened a special session dedicated to the accident, The Associated Press reported.

Deputy Emergency Minister Volodymyr Kholosha promised that his department's task "is above all directed at the people affected, their livelihood, their health, their security."

Many lawmakers demanded more help for the millions affected, and more information to answer the still lingering questions over the accident's aftermath.

"Let God not allow this to be repeated. Let God not make our grandsons relive this," said Valentyna Mashina, 55, standing near a monument to the victims in the town of Chornobyl, where 4,000 people still live - but for no more than two weeks at a time - to work in the most highly contaminated zone.