Gaza, March 21 (DPA) United Nations Secretary General Ban Ki-Moon called Sunday on Israel to lift its blockade of the Gaza Strip, as he visited the impoverished salient to examine first hand the humanitarian situation.

Addressing a news conference in the southern Strip city of Khan Younis, Ban said the 'unacceptable' blockade increased suffering while 'weakening the moderates and encourages the extremists'.

Israel imposed the tight blockade on the Strip in June 2006, after Gaza-based militants launched a cross-border raid and snatched Israeli soldier Gilad Shalit. Shalit is still being held somewhere in the Strip, and efforts to negotiate his release have so far proved fruitless.

Ban, who entered the enclave Sunday, visited two sites, a neighbourhood east of the Jabalia refugee camp in the north of the salient, targeted in last year's 22-day Israeli military offensive against Gaza militias, and a UN-sponsored housing project in Khan Younis.

Israel launched the offensive in late December 2008, in response to repeated militant rocket fire on its southern towns and villages.

Some 1400 Palestinians, most of them civilians, were killed in the 22 days of fighting, and thousands of homes and buildings were destroyed, according to human rights organisations.

'It is frustrating to see this destruction in Gaza and not being able to reconstruct,' Ban said.

'I condemn all military actions that lead to the killing of Israelis and Palestinians. Conflicts can only be resolved through negotiations,' he added.

The secretary general's visit to Israel and the Palestinian areas coincides with the tour to the region by US special envoy George Mitchell, who is due to meet with Israeli officials Sunday.

Mitchell had been scheduled to visit last week, but his trip was delayed as a result of a lingering Israeli-US dispute sparked by Israel's announcement of building new homes in an East Jerusalem neighbourhood located in the occupied West Bank.

Palestinian anger over the announcement of the new settlements scuttled an agreement to hold indirect peace talks under the aegis of the US.