The United States called for a ban on chemical weapons Tuesday, charging that ''cruel and inhumane weapons of war'' were being used in Laos, Kampuchea, and Afghanistan.
The appeal came the day after President Reagan asked Congress for authority to resume production of chemical weapons for the first time since 1969. But Eugene Rostow, director of the US Arms Control and Disarmament Agency, told the United Nations Disarmament Committee that Mr. Reagan had reaffirmed support for a complete and verifiable ban on chemical weapons.
Mr. Rostow said new evidence had confirmed the use of ''prohibited lethal mycotoxins'' in Laos, Kampuchea, and Afghanistan, which may violate the 1972 Biological and Toxin Weapons Convention.
In a letter to Congress, President Reagan said the US should resume producing chemical weapons as a deterrent, and as a lever for negotiating a ban on chemical warfare.