In a speech to the US Congress, Benjamin Netanyahu warned that a deal under discussion on Iran's nuclear programme could "pave Iran's path to the bomb" rather than block it.

But Mr Obama said Mr Netanyahu had offered no viable alternative.

Other senior Democrats - and Iran - also criticised Mr Netanyahu.

The Israeli leader's visit was controversial from the start, because the Republican speaker invited him without consulting the White House.

The US president announced he would not meet Mr Netanyahu, who is fighting in a closely contested national election in just two weeks' time.

Talks on Iran's nuclear programme are nearing a critical late-March deadline for an outline agreement to be reached.

'Hide and cheat'

In a speech to the US Congress regularly punctuated by standing ovations Mr Netanyahu depicted Iran as a "threat to the entire world".

He insisted Iran had proven time and time again that it could not be trusted.

Mr Netanyahu went on to criticise the likely contours of the deal currently being negotiated in Switzerland, where Iranian Foreign Minister Javad Zarif met US Secretary of State John Kerry on Tuesday.

"We've been told that no deal is better than a bad deal," he said. "Well this is a bad deal, a very bad deal, We're better off without it."

He said it relied heavily on international monitoring, when Iran "plays a pretty good game of 'hide and cheat' with UN inspectors".

The speech was classic Netanyahu. He mixed the politics of fear with the politics of bravery in adversity. Iran was gobbling up Middle East states - a reference to its influence in Syria, Lebanon, Iraq and Yemen - while Israel stood strong, never again allowing the Jews to be passive victims.

It was a direct intervention in American politics. Prime Minister Netanyahu wants the Congress to do all it can to block an agreement with Iran, if one is made.

Iran, he said, must change its aggressive behaviour before any deal.

Mr Netanyahu's critics say he's manipulating the close relationship between Israel and the US for political advantage. Democratic leader Nancy Pelosi said she was close to tears during the speech - because it was condescending and insulted the intelligence of Americans.

But there's no doubt that Mr Netanyahu sees the threat from Iran as real, and his skilful rhetoric will connect with many Americans. If there is a deal, President Obama will need to deploy his own considerable way with words to sell it to his own people.

(BBC)