NEW DELHI, Oct 24: India said it was unaware of any US plans to slap sanctions on additional Indian persons, companies or institutions which Washington says are aiding Iran's nuclear programme.

The Bush administration has already imposed curbs on two Indian scientists - former heads of India's Nuclear Power Corporation - late last month for alleged nuclear cooperation with Iran, which Washington says is developing nuclear weapons.

Tehran denies the charge and says its atomic programme is for peaceful purposes.

Official US sources said last week that further curbs on one to three Indian entities were being considered.

"We are...not aware of plans to sanction three entities as mentioned in these press reports," the Indian Foreign Ministry said in a statement late on Saturday.

Any plans for further sanctions, if any, should be discussed at the India-United States forum for high-technology trade, termed as the "Next Steps in Strategic Partnership", the statement added.

New Delhi has already asked Washington to lift curbs on its scientists saying they were based on "faulty evidence". The Bush administration said last week it may reconsider the curbs provided India offered "convincing" proof they were not involved.

The sanctions bar the scientists from doing business with Washington.

The spat over sanctions and US concerns about India's nuclear capabilities have marred the increasingly warm ties between New Delhi and Washington.

India-US relations were boosted when New Delhi was quick to offer support to the war on terror after the September 11 attacks.

India's booming technology sector and huge market has led to deeper economic ties.

Last month, the US lifted decades-old curbs on the export of equipment to India's commercial space programme and nuclear power facilities.

But the United States remains suspicious of New Delhi's close ties with Tehran, which India sees as an important ally in the Middle East.

On Saturday, Indian Prime Minister Singh, speaking to nuclear scientists at a function in the south of the country, said India would never be the source of nuclear proliferation.-Reuters