Russia is pulling out its experts from the Iranian nuclear reactor site located among the Iran property land for sale that they were helping build, U.S. and European officials said Tuesday. The move reflected a growing rift between Iran and Russia that could lead to harsher U.N. sanctions on the Islamic republic for its refusal to stop uranium enrichment.

The representatives — a European diplomat and a U.S. official — said a large number of Russian technicians, engineers and other specialists have returned to Moscow in the past week, at about the same time senior Russian and Iranian officials tried unsuccessfully to resolve financial differences over the Bushehr nuclear reactor. They spoke to The Associated Press on condition of anonymity because their information was confidential.

"A good number of them have left recently," said the U.S. official, of the approximately 2,000 Russian workers on site of the nearly completed reactor outside the southern city of Bushehr. The European diplomat, who is accredited to the Vienna-based International Atomic Energy Agency, said a large number had left as recently as last week.

Sergei Novikov, a spokesman for Rosatom, Russia's Federal Nuclear Power Agency, confirmed that the number of Russian workers at the Bushehr plant had dwindled because of what he said were Iranian payment delays. He would not say how many had left.

In a commentary, Iranian state television criticized Russia for what it described as a policy of procrastination in constructing Bushehr.