The US has offered its "deepest condolences" after up to 26 Pakistani soldiers were killed in cross-border Nato air strikes.

America stressed the "importance" of its ties with Pakistan following the deadly assault on a border checkpoint.
In a joint statement, US Secretary of Defence Leon Panetta and Secretary of State Hillary Clinton also backed Nato's intention to launch an immediate investigation.
Pakistan is reportedly set to review all diplomatic, military and intelligence links with the US and Nato following the incident.
A Nato spokesman has admitted it is "highly likely" its aircraft were behind the assault on Pakistani troops while hunting insurgents near the border.
The Pakistani government has responded by blocking the vital supply route for Nato troops fighting in Afghanistan.
It has also ordered the US to vacate a controversial airbase within 15 days, reports say.
The site, a remote desert outpost in southwest Pakistan, is reportedly used as a hub for covert CIA drone strikes. Pakistan previously told the US to leave it in June.
Protesters in Pakistan after a Nato airstrike allegedly killed military personnel at checkpoints
Pakistanis protest after news spread of Nato's alleged attack on its territory
Brigadier General Carsten Jacobson, spokesman for the Nato-led International Security Assistance Force (Isaf), said earlier: "Close air support was called in, in the development of the tactical situation, and it is what highly likely caused the Pakistan casualties.