WRAPUP 6-Myanmar mourns dead, U.N. reports aid progress

* Myanmar starts three days of mourning

* Top U.N. aid official in talks with Myanmar PM

* Myanmar to allow Japanese aid workers (Adds U.N. Secretary General quote)

By Aung Hla Tun

YANGON, May 20 (Reuters) - Flags flew at half-mast across Myanmar on Tuesday for the victims of Cyclone Nargis as the U.N.'s top aid envoy pressed the military government to allow foreign helicopters to fly in supplies to survivors.

The first day of the three-day mourning period passed in torrential rain and diplomatic prodding of the reclusive generals to allow more international aid after a cyclone that struck two weeks ago, leaving nearly 134,000 dead or missing.

"There are still a lot of supplies needed to get in in the future in terms of food, but not just for now but for some months to come," U.N. humanitarian chief John Holmes told reporters after meeting Prime Minister Thein Sein.

He said military-run camps in the devastated Irrawaddy Delta for the homeless "seemed well organised" but most survivors were still without shelter.

Holmes said he had discussed the use of helicopters with the general, who "took note" of his suggestion.