Gaza City, March 22, 2010, SPA -- 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. US special envoy George Mitchell, meanwhile, handed Israeli Prime Minister Benjamin Netanyahu a formal invitation to meet with President Barack Obama in Washington, amid reports Israel and the US are trying to defuse a smoldering row sparked by an announcement of new Israeli construction in the occupied Al-Quds (East Jerusalem), according to a report of the German Press Agency (DPA). Addressing a news conference in the southern Gaza Strip city of Khan Younis, Ban Ki-Moon said the "unacceptable" blockade increased sufferings while "weakening the moderates, and encourages the extremists." Ban Ki-Moon, who entered the enclave Sunday morning, visited two sites, a neighborhood east of the Jabalia refugee camp in northern Gaza, and a UN-sponsored housing project in Khan Younis. The UN plans to build 150 new homes at the Khan Younis site to house families who lost their homes during the Israeli offensive in late December 2008, according to a report of the German Press Agency "DPA". Some 1,400 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 organizations. --MORE 12:42 LOCAL TIME 09:42 GMT www.spa.gov.sa/761224