Britain has published a formal defense white paper introducing the idea of developing chemical warfare weapons that could be used by NATO to deter or retaliate against Warsaw Pact gas attacks in Europe.

The white paper, presented Wednesday by Defense Secretary Francis Pym, also outlined British plans to develop a modest mobile strike force that could work with American forces in trouble spots such as the Persian Gulf region and suggested arming women.

The chemical warfare notion was featured in British newspapers today, with varying degrees of concern expressed. The British, who were repelled by their World War I experience with poison gas, are likely to move cautiously in considering chemical weapons. Pym emphasized that he had so far approved only a study of reversing British policy and resurrecting chemical warefare research and development.

Because the Soviet Union and its Eastern European allies are continuing to develop and stockpile such weapons, Pym said it was necessary for Britain and NATO to consider developing a deterrent capability.

"I think we ought to ask the question," Pym said. "No conclusions or decisions have been reached."

Other sources said Britain also is consulting with the United States and other NATO allies. These countries have been trying unsuccessfully to negotiate with the Soviet Union to reach a verifiable ban on chemical warfare through expansion and strengthening of the 1925 Geneva protocol.

Pym's white paper stated that the Soviet Union, unlike NATO, has "a major capability for offensive chemical warfare" and its military forces are "fully equipped to operate in a chemical environment."

Should Britain move to develop chemical weapons, it would adopt a stance similar to the U.S. posture.

Objectives of U.S. chemical warfare policy, as enunciated by Defense Secretary Harold Brown earlier this year, are "to deter the use of chemical weapons by other nations and to provide an option to retaliate in kind should deterrence fail."

The U.S. is stockpiling chemical weapons and developing, but not deploying, binary bombs. Binary weapons carry two agents that become lethal when they are mixed together. President Carter this year asked Congress for money to design a binary chemical factory, but did not commit himself to building it.

The British white Paper also revealed that Britain is developing a modest mobile strike force to assist in emergency allied intervention in trouble spots beyond NATO territory, including the Persian Gulf and Indian Ocean. Planning for this began after the Soviet invasion of Afghanistan at the end of last year.

Options being considered include reorganizing the British Home Defense force so that men and equipment could be mobilized quickly for action anywhere in the world, providing more transport aircraft and naval support ships, and stockpiling some equipment in or near the Persian Gulf area.

Because of Britain's heavy military commitments in West Germany, where in assumes the full expense of maintaining NATO's British Army of the Rhine, and in Northern Ireland, a British mobile strike force would necessarily be small and capable largely of supporting a similar American strategic force or cooperating with other allies. The foreign secretary, Lord Carrington, has indicated Britain's willingness to help protect Western interests and the independence of nonaligned nations in the region around Afghanistan.

The white paper, which did not mention the previously often-used word "detente," concentrated on the need for Britain and NATO to counter a growing potential Soviet threat to Western Europe and other parts of the world. It stated that the Soviet invasion of Afghanistan shows that "our opponents have both the power to make new territorial and strategic gains and the nerve to use that power."

Thatcher's government will increase British defense spending next year by 3.5 percent, slightly more than NATO nations have agreed to do, and will concentrate on improving Britain's air defenses and its independent submarine-launched nuclear deterrent.

The government has not yet decided what to do when Britain's present four Polaris submarines need to be replaced sometime during the 1990s, but the Defense Ministry is still known to favor purchasing five U.S.-built Trident submarines and missile systems, to be armed with British-made nuclear warheads.

Pym said the government also was considering giving guns to women in the British military for the first time. Their role has been growing, partly because they are now easier to recruit then men."

"The arming of women seems to be the kind of change we need," Pym said. "Some women would feel they would be fulfilling a more important role if they carried weapons."