ALMATY, Kazakhstan -- Kazakhstan agreed Tuesday to throw open its huge nuclear arsenal to regular checks by the world's nuclear watchdog agency for the first time.


Hans Blix, director general of the International Atomic Energy Agency, told a news conference that the IAEA's checks would help to prevent dangerous nuclear substances being put to aggressive use. "It is important that other nuclear states can have confidence that other states are adhering to the nuclear non-proliferation treaty," Blix said after signing a "safeguards agreement" with Kazakh Prime Minister Sergei Tereshchenko.


The agreement will allow IAEA inspectors to check that plutonium and other substances are not being smuggled into dangerous hands from Kazakhstan's nuclear arsenal of 104 SS-18 intercontinental ballistic missiles.


Kazakhstan, which gained independence from the former Soviet Union in 1991, late last year signed the nuclear non-proliferation treaty, which aims to prevent the spread of nuclear technology to non-nuclear countries.


Blix said that much progress has been made in establishing control over Kazakhstan's nuclear facilities but that more needed to be done. "I think they still need to strengthen their verification system further," he said.


Such a system checks that dangerous substances are not being diverted to non-peaceful uses.


A team of IAEA specialists monitoring radiation levels around the former Soviet Union's nuclear testing site in Semipalatinsk, in northeastern Kazakhstan, has found that radiation is not significantly above normal levels, Blix said. An increase in birth deformities and illnesses has been recorded around Semipalatinsk from an era of nuclear tests there which ended when the U.S.S.R collapsed. Blix said it is possible that radiation levels remain high underground and he did not deny the possibility that radiation may have been high around Semipalatinsk a few years ago.


International donor organizations, the West and Japan have pledged more than $1.4 billion in credits to Kazakhstan this year, partly in recognition of its cooperation on nuclear issues.