Washington: Saudi Arabia's former ambassador to the US said on Tuesday there was ‘ample and heinous' evidence that Iran was behind an alleged plot to kill the current Saudi envoy to Washington.

Prince Turki Al Faisal, who also once served as Saudi Arabia's intelligence chief, told reporters that if Tehran failed to prosecute Iranians linked to the plot, Riyadh may take the case to the United Nations.

"We have seen ample and heinous evidence in the uncovering of an assassination plot against the Saudi ambassador to the United States," he said, adding the evidence "indicates the depths of depravity and unreason to which the Ahmadinejad regime has sunk. Fortunately, this plot was foiled."

Turki also said it was ‘inevitable' that Syria's president will step down in the face of growing popular opposition.

The Saudi prince is no longer a government official and said he was speaking as a private citizen. But he is an influential member of the royal family and serves as chairman of the King Faisal Centre for Research and Islamic Studies. The US charged in October that agents linked to Iran's Quds Force — an elite wing of the powerful Revolutionary Guard — were involved in a plot to kill Saudi Ambassador to the US Adel Al Jubair. Iran has called the accusation ‘baseless.'

Prince Turki called the plot ‘the tip of the iceberg,' saying Iran was ‘meddling' in the affairs of many other countries, including Lebanon, Turkey, Pakistan and especially Iraq. The Saudi government has also accused a terror cell linked to Iran of plotting to blow up its embassy in Bahrain, as well as the causeway linking the island kingdom to Saudi Arabia.