West German Defense Minister Hans Apel, whose country plays a key role in NATO's plans to modernize its arsenal of nuclear missiles in Europe, said today the conditions laid down by Bonn to allow those missiles to be stationed on German soil now "have been met."

Apel's remarks to reporters here were the first public indication that West Germany now has enough partners among other nonnuclear countries in Western Europe to take part in the NATO plan. The missiles involved would be the first in Europe capable of striking the Soviet Union.

West Germany, which does not have atomic weapons of its own and is wary of being portrayed as becoming a nuclear power, has insisted that it not be alone in accepting the new Pershing II and cruise missiles that are described as a balance to new Soviet arms already in place.

Acceptance of the plan had been indicated yesterday by U.S. officials at the two-day meeting of the 11-nation Nato nuclear planning group here. Apel said today that the Italian defense minsiter also had voiced support for accepting the new weapons.The Belgian defense minister gave "somewhat qualified support," Apel said, but let it be understood that the Brussels government will give its consent when the time comes for the final decision at the full-scale NATO meeting in Brussels next month.

With an eye to West German-Soviet relations, Apel also went to some lengths to portray the German role only as one of allowing its soil to be used. He said the weapons would be on U.s. bases, under U.S. control, with no "two-key" control system as is used by some countries where outer U.S. weapons are based, and that American soldiers rather than West Germans would provide security.

The statement is especially significant because it comes at a time when the Dutch government still is in disagreement with the NATO plan. It provides another indication that NATO would go ahead even if the Dutch do not take part.

A final communique and press conference statements by U.S. Defense Secretary Harold Brown, British defense chief Francis Pym and NATO Secretary General Joseph Luns made clear the determination of NATO to go ahead with no changes in the plan to deploy about 572 of the new missiles.

The Dutch want NATO to decide only to produce these weapons and to wait two more years before a decision on installing them to see how arms control talks with the Soviets work out.

While there is widespread speculation that the Dutch government may find a way to join the others by next month's meeting, there was an extraordinary degree of open criticism of the Dutch position here.

Brown called the production-only stance "completely unrealistic," saying there is no way that Congress would approve billions of dollars to produce such weapons if Western Europe would not commit itself to accept them. Apel, in private, is said to have called the Dutch stance "illogical and useless," one that would weaken the chances for productive arms control negotations and could even hurt chances for U.S. ratification of the second strategic arms limitation treaty.

British Minister Pym said, "We have given great attention already to the Dutch views and taken them into account. But we can go no further down that road. The whole of the alliance in involved."

Brown said the United States would absorb "the great bulk" of of production costs, estimated at more than $4 billion, with the other sharing in much more modest operating expenses.

In their communique, the ministers also boosted the idea of a unilateral withdrawal from Europe of about 1,000 older U.S. atomic warheads. This proposal, Brown indicated, is likely to be adopted at the forthcoming Brussels meetings.

In part, this would be linked to the new modernization plan and meant to symbolize NATO getting rid of older, less reliable weapons for a smaller number of better ones. It could soften Dutch opinion as well. But it also is meant as a partial response to the recent statements of Soviet President Leonid Brezhnev, who said the Kremlin would pull back up to 20,000 troops and 1,000 tanks from East Germany.

The meeting that ended here today was not intended as a decision-making session but rather to prepare final positions for the Brussels session.

Of the missiles to be deployed, 204 are to be based in West germany, with the rest in Britain, Italy, Belgium and, possibly, the Netherlands.