House-Senate conferees, in a move that caught the Reagan administration by surprise, agreed to delete funds for military sales to Jordan from the supplemental appropriations bill they approved Wednesday.

Administration officials say that the action could further complicate their efforts to draw Jordan's King Hussein into Middle East peace talks by sending a signal to Jordan that the United States may not be a reliable ally and protector.

"If you can't even get the Congress to approve $15 million for a friendly country, regardless of whether they feel the king is willing to risk his neck, then Jordan might be forgiven for reaching the conclusion that the United States is unwilling to deliver on even the most remotely controversial commitment, if that commitment is not acceptable to Israel," a State Department official said.

Last April, Hussein announced that Jordan would not participate in the peace talks, after the administration had spent months trying to persuade him to play a key role.

In the supplemental appropriations bill, the administration had requested $35 million in foreign military sales credits for Jordan. The House voted to give Jordan nothing, while the Senate agreed to appropriate $15 million.

When conferees gathered to iron out their differences, according to a Senate aide, they were faced with the question of how to lower allocations to several countries.

One of the conferees suggested that language be included saying that none of the money in the bill be used for Jordan, and others agreed, with minimal debate.

Several in attendance described the discussion as "casual."