The Pentagon is proceeding in great secrecy to produce neutron "killer" shells for its nuclear artillery forces in Europe, according to knowledgeable sources.

"We are moving," said one informed critic of the program, "toward a battlefield neutron force."

This development has not previously been revealed. It was disclosed earlier this month that the Pentagon intended to produce a neutron warhead for its land-based missile, the Lance.

It is now known that production of a similar projectile for artillery forces only awaits congressional funding and President Carter's approval. The new warheads would be fired from 8-inch and 155-millimeter howitzers.

Conventional nuclear weapons destroy targets with blast, heat and radiation. Neutron warheads, on the other hand, are designed to kill people by radiation alone.

The artillery pieces that would fire them include more than 400 of the 8-inch howitzers and some of the 1,500 smaller 155-millimeter howitzers assigned to U.S. forces in Europe. Some of the 155-millimeter cannon are in units of North Atlantic Treaty Organization allies.

The Defense Department's assistant secretary for public affairs, Thomas Ross, said last evening that "this is a matter of legitimate high classification" and "there would be no comment."

Money for production of the 8-inch neutron warhead as well as the Lance enhanced radiation warhead is contained in the Energy Research and Development Administration portion of the $10.2 billion fiscal 1978 public works money bill now before the Senate.

ERDA also sought research funds for the neutron version of the 155-millimeter shell. The House deleted the money from the bill and the Senate has yet to act on it.

Proposed production of the 8-inch and Lance neutron warheads represents the first time a tactical nuclear weapon has been procured that was specifically designed to kill people solely by radiation.

Proponents of the move to enhanced radiation battlefield warheads argue, as one Defense Department official did yesterday, that they are "a more positive deterrent" than traditional tactical nuclear weapons because they create "relatively little collateral damage."

By cutting down heat and blast of a nuclear explosion by a factor of 10, the new enhanced radiation warheads are more likely to be used, he argued.

Defense Department officials argue that since most casualties from past nuclear explosions came from burns and blast effects, the new warheads - which expose individuals to high doses of radiation but leave buildings standing - would be "more humane."

Opponents of the new weapons have been limited in their ability to debate the matter publicly because of is high classification.

"It's all Q material," one source said yesterday, referring to the traditional Q clearance required of anyone dealing with highly classified atomic weapons matters.

Sen. Mark O. Hatfield (R-Ore.) introduced an amendment during Senate Appropriations subcommittee hearings on the public works money bill that would have deleted production funds for the Lance warhead.

Debate over the Hatfield amendment was held in executive session at the request of Sen. John C. Stennis (D-Miss.), chairman of both the subcommittee and the Senate Armed Services Committee.

Hatfield's amendment lost on a 10-to-10 tie vote but he plans to offer it again when the public works bill gets to the Senate floor next week.

No one yesterday could explain why the enhanced radiation warhead for the Lance was declassified while those for the 8-inch and 155-milimeter neutron shells were not.

The idea of the neutron warhead has been studied in U.S. nuclear weapons laboratories for years but the Army traditionally balked at buying it because it did not believe a high enough radiation dose could be generated to instantly kill or incapacitate an enemy force.