West German Chancellor Helmut Kohl, the first in a six-week parade of allied visitors, informed President Reagan yesterday of his "full support" for the U.S.-Soviet arms talks scheduled for next month and said deployment of new U.S. missiles in western Europe must continue until an East-West accord is reached.

U.S. and European leaders anticipate a major campaign by the Soviet Union and antinuclear groups in Europe for a halt in U.S. deployments while arms negotiations are renewed. But Kohl told reporters that he, like Reagan, is opposed to one-sided, advance "concessions" to the Soviets.

After a two-hour meeting and working luncheon at the White House, Reagan and Kohl unveiled a three-page joint statement calling for "continued close and intensive consultations" among the western allies as the United States and the Soviet Union head into a new phase of arms diplomacy.

In a departure ceremony on the White House grounds, Kohl said he and Reagan "consider it important that the western European allies be associated with this process, thus creating the conditions for the renewed bilateral U.S.-Soviet dialogue being placed on a wider foundation in the medium and long term."

The joint Reagan-Kohl statement said their two countries see it as "imperative" that U.S. missile deployments continue as envisaged by NATO in a 1979 decision. The statement repeated the well-established allied position that the deployments could be halted, modified or reversed if the Soviets agree to a "balanced and verifiable" agreement, which has eluded the two nuclear superpowers.

Kohl will be followed in visits to Reagan by British Prime Minister Margaret Thatcher on Dec. 22, Japanese Prime Minister Yasuhiro Nakasone on Jan. 2 and Belgian Prime Minister Wilfried Martens on Jan. 14. In the meantime, Secretary of Defense Caspar W. Weinberger will meet NATO defense ministers in Brussels Dec. 3 and 4, and Secretary of State George P. Shultz will meet NATO foreign ministers in Brussels Dec. 13 and 14.

U.S. officials said Kohl did not request a special mechanism for consulting the allies about the discussions between Shultz and Soviet Foreign Minister Andrei A. Gromyko, scheduled for Geneva Jan. 7-8, or during any arms control negotiations that may follow. But the officials said Kohl was promised intense consultations using existing channels, along the lines of those that preceded the beginning of the U.S. missile deployments in Europe a year ago.

On the substance of U.S. positions for the forthcoming talks, the consultations with Kohl were described as very general. The West German leader said Reagan acquainted him with "American ideas" about the arms control posture but the U.S. briefer told reporters these were broached in only the most general way because Reagan has yet to make decisions about specific U.S. positions.

A National Security Council meeting of Reagan and his top advisers was scheduled to concentrate on the arms talks following the luncheon with Kohl but a senior State Department policy-maker refused to discuss it. Referring to an unusual three-page secrecy agreement signed this week by participants in interagency discussions about U.S. arms positions, the official said: "I signed a paper saying if I talked, I'd be thrown in the slammer."

The same official, during a briefing for reporters at the White House, placed much emphasis on a paragraph in the Reagan-Kohl statement calling for "an improved conventional defense posture" in Europe in order to redress a "steadily growing imbalance" in favor of the Eastern bloc and thus to reduce the likelihood that nuclear weapons would be used in any clash.

Speaking out strongly along the same lines, U.S. Gen. Bernard W. Rogers, the NATO supreme commander, warned in Los Angeles that "under current conditions we have no recourse but to resort to nuclear weapons [in case of war] because we don't have sufficient men, ammunition and conventional weapons" to fight a non-nuclear war.

The Reagan-Kohl statement made it clear that any conventional-forces buildup in Western Europe would have to be based on what it called "a coherent alliance approach" involving the efforts of NATO as a whole. A U.S. official said one of the reasons behind such a new effort was to placate members of Congress who are demanding that European countries do more in their own defense if they want American troops to remain on the continent.

In the news conference following the White House meeting, however, Kohl seemed less than enthusiastic about any increase in military expenditures to build up NATO's conventional forces. While he sees the "logic" of such increases, he said, the "political implications" must also be considered.

Kohl, following a busy day of talks with Reagan, Shultz, Weinberger, Vice President Bush and others, departed for Germany last night.