The Pentagon and western European officials took issue yesterday with a report Sunday in The Washington Post that Britain, West Germany and Italy have asked the United States to go ahead with production of a new 155-mm neutron artillery shell.

The Post reported that Reagan administration officials had told congressional committees earlier this year that the three allies wanted the neutron shell because a new cannon they were developing could not fire the older, 155-mm nuclear shell stockpiled in Europe.

The report added that the allies' needs were cited in a new administration push for Capitol Hill approval on production of the controversial neutron weapon, which Congress had turned down in 1981 and 1982.

A Pentagon spokesman told Reuter news agency yesterday that the three nations had asked for a new 155-mm shell to fit their new cannon but that no decision had been made as to whether it would carry a neutron warhead.

At the economic summit in Williamsburg, a foreign ministry spokesman said West Germany had been told about U.S. development of the 155-mm neutron shell.

"We took note of it, that's all," the spokesman said. "We certainly didn't request it."

A British official said, "Production of those weapons on U.S. territory is a matter for the U.S. government."