The United Nations's undersecretary-general for humanitarian affairs warned Israel against an invasion of the Gaza Strip and said that the crisis in the South can be solved only by diplomacy.

"The only thing that will make a lasting difference is a peace settlement," he said. "You can't stop these problems militarily. They have to be solved through negotiations."

In an interview with Haaretz after his visit to Sderot, Sir John Holmes said that the response to the Qassam rocket attacks must be proportional from a humanitarian point of view. The former British diplomat, who had been involved in negotiations regarding Northern Ireland, said that despite the terrorism, the British government never considered bombing that region, and sought other means to resolve the crisis.

Holmes said he was aware of the domestic pressure on the Israeli government to respond to the Qassam attacks, as well as the differences between the situation here and in Northern Ireland, but said there were no magic formulas.

The senior UN official had requested to meet with Foreign Minister Tzipi Livni and Defense Minister Ehud Barak, but was turned down.

Regarding the continued Qassam rocket attacks, Holmes said during a visit to Sderot, "We condemn absolutely the firing of these rockets. There's no justification for it. They are indiscriminate."

Two weeks ago, Israel's ambassador to the UN, Dan Gillerman, attacked Holmes for a statement he issued against collective punishment in the Gaza Strip, while ignoring the rocket attacks against Sderot.

Holmes said yesterday that Gillerman apologized when he learned that the condemnation also included specific references to the rocket attacks on Sderot.