KIEV, Ukraine -- Urging all nations to be extremely cautious with nuclear energy, Ukraine's president thanked donors for financing the construction of a new, safer shelter over the damaged Chernobyl reactor on the 26th anniversary of the world's worst nuclear disaster.
A woman cries in front of a memorial dedicated to firefighters and workers who died after the Chernobyl nuclear disaster during a night service near the Chernobyl plant in the city of Slavutych on April 26, 2012.
President Viktor Yanukovych spoke during a ceremony Thursday inaugurating the initial assembly of a gigantic arch-shaped steel containment building to cover the remnants of the exploded reactor.
The structure — weighing 20,000 tons and big enough to house New York's Statue of Liberty — is due to be completed in 2015, allowing the delicate and dangerous job of dismantling the reactor and cleaning vast amounts of radioactive waste still around it to begin.
"The Chernobyl disaster underscored that mankind must be extra careful in using nuclear technologies," Yanukovych said.
"Nuclear accidents lead to global consequences. They are not a problem of just one country, they affect the life of entire regions."
The April 26, 1986, explosion spewed a cloud of radiation over much of the northern hemisphere, forcing hundreds of thousands of people from their homes in heavily hit areas of Ukraine, Belarus and western Russia.
The Soviet government initially tried to hush up the explosion and resisted immediately evacuating nearby residents.
It also failed to tell the public what happened or instruct residents and cleanup workers on how to protect themselves against radiation, which significantly increased the health damage from the disaster.
A shelter called the "sarcophagus" was hastily erected over the damaged reactor, but it has been crumbling and leaking radiation in recent years and a new confinement structure is necessary.
Yanukovych said 2 million people have been hurt by the tragedy and it is the state's obligation to protect and treat them.
But his reassurances fell flat with some Chernobyl cleanup workers and victims.
About 2,000 protesters staged an angry rally Thursday outside parliament in Kiev, demanding an increase in compensations and pensions.
In Minsk, the capital of Belarus, more than 1,000 demonstrators took part in a march protesting plans to build the former Soviet republic's first nuclear power station, in the town of Ostrovets near the Lithuanian border.
The plant will be built by Russia.
"This project is approved by the Kremlin, which through the nuclear power plant is binding all of the energy of Belarus to itself," said Anatoly Lebedko, one of the protest leaders.
A similar march in 2011 was banned by the authoritarian government, which routinely represses opposition actions, but this year's march was sanctioned and police did not interfere.
Yanukovych also thanked international donors for pledging €740 million ($980 million) to build the new shelter and a nuclear fuel waste facility.
The biggest donors are the Group of Eight industrial nations, including Japan, which itself is still recovering from last year's horrific Fukushima nuclear disaster.
"It feels good to note that Ukraine wasn't left alone with its pain. We felt that the whole world came to our rescue," Yanukovych said.
Vince Novak, director of the Nuclear Safety Department with the European Bank for Reconstruction and Development, which manages and co-funds the project, praised Ukraine's commitment to the cleanup.
"It is definitely important for the bank and for the donors to know that there is a strong commitment in Ukraine to do everything necessary to ensure that the Chernobyl project progresses well," Novak told The Associated Press.
"We have no room or margins for delay, for errors or for poor performance."