Cambridge city officials yesterday reissued an order to halt testing of lethal nerve gas at a laboratory two miles north of the University.

City Health Commissioner Dr. Melvin Chalfen first ordered the Arthur D. Little consulting firm to stop its testing last March. The company immediately countered with a court injunction. Permitting it to continue its work with the chemical warfare agent.

Chalten called the latest order "part of a continuing process" in a legal struggle between the city and the company, which is under a Defense Department contract to develop an agent to neutralize nerve gas and other less toxic gases.

He added that reissuing the regulation was a "legal technicality" necessary to reemphasize the city's opposition to the testing. The first order was to remain in effect until the city received two separate reports on the safety of the testing. Both reports have been received and examined in court, and the case has been continued until Oct. 31.

One of these reports, issued by an committee of 16 area doctors and scientists, warned that the accidental release of one quart of nerve gas--the maximum amount at the laboratory at any given times--could spread a fatal dose as far as three tenths of a mile away.

The Committee report stated that motorists, a bowling alley, a disco, nearby athletic field, and residential neighborhoods all he within that radius.

Officials at Little deny that their testing presents any danger and say testing presents any danger and say that the laboratory meets all federal safety regulations.