At least five people, including four paramilitary troops were killed in a roadside blast in northwestern Pakistan on Sunday, an official said.
The blast took place in the town of Mamoond, some 25 kilometres (15 miles) from Khar, the main town of Bajaur, one of the country's seven semi-autonomous tribal districts, where the army has been battling Taliban militants.
He said a four-country group including Pakistan, China, the USA and Afghanistan could be expanded to include other countries with influence over the Taliban.
The levy personnel was on routine patrolling of the area when the militants detonated the IED through remote control device as their vehicle reached the spot, it said.
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Security forces have cordoned off the area and kicked off a search operation in the surrounding areas for the culprits.
A few hours after the blast, the Tehreek-e-Taliban Pakistan (TTP) terror group, also known as Pakistani Taliban, released a statement, claiming responsibility for the attack. Security in the region has improved in recent years after the Pakistani military mounted offensives there against the al Qaeda-linked Pakistani Taliban, which is considered the country's biggest security threat.
The Financial Times reported that officials familiar with the Pakistan prong of Washington's new "AfPak" strategy - which involves an open-ended commitment in Afghanistan and praise for India - say it has yet to be fleshed out.