CAIRO/JERUSALEM, Aug 1 (Reuters) - President Donald Trump's Middle East envoy became the first high-profile U.S. official to visit Gaza since the war began, touring a U.S.-backed aid operation on Friday that the United Nations says is partly to blame for deadly conditions in the enclave.

The UN says at least 1,373 Palestinians have been killed near aid sites since late May - Israel says its forces do not intentionally shoot civilians.

Steve Witkoff, the United States special envoy to the Middle East, visited a controversial US-backed aid distribution site in Gaza on Friday, where hundreds of Palestinians have died in recent weeks as they try to access what little food has entered the enclave.