The Communist Party of India (Marxist) on Monday described Prime Minister Manmohan Singh's statement on Indo-US nuclear deal as 'untenable', saying President George W Bush was bound by the legislation enacted by the US Congress.

"The prime minister's assertions are untenable as George Bush is bound by the legislation passed by the US Congress," CPI(M) leader Sitaram Yechury, a Rajya Sabha member who sat through Singh's speech in the Lok Sabha gallery, told reporters.

He argued that the Dr Singh has pointed out that US would address India's concerns on the deal, but President Bush was bound by the new law.