An overwhelming majority of the US Senate has urged President Barack Obama to impose “crippling sanctions” on Iran’s financial system in an effort to block its suspected nuclear programme.

About 92 of the Senate’s 100 members wrote to Obama, saying it was time to impose sanctions by cutting off the Central Bank of Iran.

“The time has come to impose crippling sanctions on Iran’s financial system by cutting off the CBI [Central Bank of Iran],” the letter said.

Republican senator Mark Kirk and Democratic senator Chuck Schumer said it was time to “increase the economic pressure” on Tehran with “a comprehensive strategy” to address Iran’s defiance of global sanctions aimed at forcing it to freeze its uranium enrichment programme.

Iran has always denied accusations from Western governments that it is seeking to develop nuclear weapons, insisting that its nuclear programme is for peaceful purposes.