They are eager to restart their lives, but it is unclear if they will have intact homes to return to and their safety is also far from certain, the UN humanitarian affairs chief has warned.

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"The security situation is not going to be 100 per cent calm in these areas overnight and we must recognise that," John Holmes said on Friday at the end of a visit to Pakistan.

Holmes told Al Jazeera that he had visited Buner and the situation seemed "at least satisfactory" for the displaced to return.

"We have not been able to visit other areas so we can't say if conditions are right," he said.
"The most important thing is that the process must be voluntary and the conditions do have to be right on the ground, in terms of security and the restoration of basic services like power and water, telephone, police force and so on," he told Al Jazeera.

The refugee crisis in unlikely to end soon as military operations continue [GALLO/GETTY]
"If they are right, of course we support return because no one wants people to stay where they are any longer than they need to."

Nearly 400,000 people are believed to have returned to Buner already.

But many residents of the Swat valley remain concerned about the situation there as sporadic clashes continue to break out despite the military controlling the towns and all major communication routes.

And their return is unlikely to end Pakistan's refugee crisis, as the military is preparing for a major offensive in neighbouring regions.

The earlier military operation began after fighters poured out of bases in the Swat valley into the neighbouring district of Buner and moved within 96km of the capital Islamabad.