The United States and its Group of Seven partners agreed Thursday to spend $20 billion over 10 years to help Russia dismantle its nuclear, biological and chemical weapons stockpiles, The Associated Press has learned.

A senior U.S. official, speaking on condition of anonymity, said President Bush and Russian President Vladimir Putin sealed the deal in their one-on-one talks as an economic summit of the world's industrial powers drew to a close.

Putin told Bush that Russia would abide by a series of conditions under which the United States and leaders from Europe, Japan and Canada would put up the money.

Under the proposal, which was being announced later Thursday at the leaders' isolated summit site in the Canadian Rockies, the United States would send $1 billion a year for $10 years on the program. Its partners from Europe, Japan and Canada would contribute a similar amount over the same time period, the official said.

He spoke on condition of anonymity shortly after the Putin-Bush meeting broke up.

Russia's obligations include providing the G-7 partners access to disposal sites, such as facilities where nuclear submarines are dismantled, the official said. Russia also has ensured adequate auditing and oversight authority to its partners.

The agreement, long sought by the United States, is part of a broader campaign to increase cooperation between the United States and Russia on international issues such as nuclear proliferation. Bush and Putin recently agreed to reduce their nuclear stockpiles, but international leaders have worried that the materials could fall into the hands of terrorists.

In their meeting, Bush hailed Putin as a "strong ally" and the leaders committed their countries to a united fight against terror.