'No indication Iran orchestrated embassy attack,' Biden says

US Vice President Joe Biden said he had no evidence the attack on the British embassy in Tehran was orchestrated by Iranian authorities, but it was another example of why the country was a "pariah".

Biden, wrapping up a three-day visit to mark the end of the American war in Iraq, played down the risk of Iran exploiting the departure of US troops by the end of the year.

He also said the threat of instability in Syria spilling across its borders was not grounds for President Bashar al-Assad to stay in power.

"I don't have any indication how and/or if it was orchestrated," Biden said in an interview, of the attack on the British embassy on Tuesday.

"But what I do know is that it is another example to the world and the region that these guys are basically a pariah internationally."

Biden conducted the interview at Arbil's sleek new airport before heading for a meeting with Kurdish Regional Government President Massoud Barzani.

The departure of US forces leaves Iraq with no effective air cover and little real military protection for its long borders with Iran or Syria.

However, Washington is not discussing another defense pact to replace the one that expires at the end of 2011, Biden said.

"We are talking about putting Iraq in a position to be able to provide its own air cover, its own defense capabilities, and there is no credible air threat to Iraq now," he said.

"So there is no discussion other than selling them F-16s, training them and preparing them for receiving those planes."

Iraq is purchasing US-made F-16 fighter jets and Abrams tanks as part of its efforts to build up its conventional military capabilities to protect its borders after years of focusing on counter-insurgency to combat Sunni insurgents tied to al Qaeda and rival Shi'ite militias.

"Does anybody really think Iran is contemplating invading Iraq. I don't think so," he said with a rhetorical shrug.