“It’s crucial that the process is consulted and voluntary. People are not to be pushed into returning before they are ready,” UN Under-Secretary General for Humanitarian Affairs John Holmes told reporters in Islamabad.

Pakistan announced on Thursday that nearly two million displaced people could start going back to Swat and three neighbouring districts from July 13. The country, however, did not formally announce an end to the military offensive.

The government in Islamabad is looking for the earliest return of the refugees since it could lose the vast public support for the military operation if the humanitarian crisis in the wake of the displacement is further aggravated.

Holmes said while his organization wanted to see the internally displaced persons (IDPs) return to their homes as soon as possible, the security situation needed to be improved and the basic services, including health facilities, restored.

The visiting UN official said the conditions were satisfactory in Buner, where 380,000 people who fled the fighting had returned to their homes. But he said his organization could not give any guarantee about Swat. “We have no access to that area.”

“The worst of all possible worlds would be if people went back home to some of the areas and then had to leave again because the situation was not satisfactory,” Holmes said. “The return has to be sustainable.”

He warned that if the return of displaced persons was not voluntary, the organization might have to cut its support for the process.

“If the returns are done in a way that we have great difficulty with them, then that would affect the degree to which we would be able to support those operations,” he said.

Thousands of military and paramilitary troops launched the offensive in Swat, formerly a popular tourist destination about 140 kilometres north-west of Islamabad, and nearby districts in late April after the Taliban violated a peace deal.

The government says it has eliminated some 1,700 militants and gained control over most of the areas after more than eight weeks of intense fighting, which have seen 158 soldiers killed and over 500 wounded.

But unknown numbers of surviving Taliban, including their leader Maulana Fazlullah, have retreated to the mountains and are continuing low-scale resistance against the security forces, leaving many locals unsure whether to return.