U.S. military officials have delayed for up to a week the escort of three more reflagged Kuwaiti oil tankers, until sophisticated mine-sweeping and other protective forces arrive in the Persian Gulf, Defense Department sources said yesterday.

The forces are being sent following the mine damage to a reflagged tanker during the first convoy and because Iran has raised new threats of retaliation against the United States. Within the next several weeks there will be about 24 U.S. Navy warships and support vessels and more than 15,000 U.S. military personnel in and around the gulf, the largest deployment since a naval task force challenged Libya's "line of death" in the Gulf of Sidra early last year.

Meanwhile, more than 100 Democratic members of Congress are asking the U.S. District Court here to force President Reagan to invoke the War Powers Resolution and allow Congress to decide whether U.S. warships should continue to escort Kuwaiti tankers that now fly the U.S. flag. The Persian Gulf has served as a major battleground in the 7-year-old war between Iran and Iraq.

"This is exactly the sort of situation the War Powers Resolution was designed to deal with," said Rep. Mike Lowry (D-Wash.), one of the lawmakers behind the suit. "It is indisputable that American forces in the Persian Gulf face imminent hostility and the situation is becoming more dangerous every day."

The legal maneuver by the members of Congress follows a week of reports that new U.S. military forces are being sent to the Persian Gulf to provide additional support to the controversial escorting operation.

The second convoy of tankers and their American warship escorts originally had been scheduled to set out late this week. But the helicopter carrier that will transport eight Sea Stallion mine-hunting and sweeping helicopters to the gulf is not expected to leave the island of Diego Garcia in the Indian Ocean for its three- to four-day voyage to the gulf until today, Pentagon sources said.

The sources said the Joint Chiefs of Staff decided formally on Wednesday to postpone the operation "to let equipment arrive" in the gulf.

Adm. William J. Crowe Jr., chairman of the Joint Chiefs, and Defense Secretary Caspar W. Weinberger spent an hour with top congressional leaders yesterday in a closed-door Pentagon meeting to discuss the gulf operations.

House Armed Services Committee Chairman Les Aspin (D-Wis.), who has criticized the military as being short-sighted in the face of threats such as mines, said he left yesterday's session "feeling a little better.

"The military is at least beginning to think in terms of what's the unusual," Aspin said. "I don't know if it's going to work."

Secretary of State George P. Shultz denied reports yesterday that the reflagging of the three tankers was postponed because a high-level Iranian delegation was in Kuwait trying to persuade that country to abandon the operation. The report of the alleged diplomatic negotiations was published in The London Independent newspaper yesterday.

"I saw that report, and as far as I know, there's nothing to it," Shultz told reporters. "As far as our reflagging operation is concerned, it proceeds according to our schedule, and there hasn't been any particular delay in it."

The newspaper said the Iranians had offered to stop attacking Kuwaiti shipping interests if the Kuwaitis would cancel the escorting arrangements with the United States. Kuwait has been allied with Iran's opponent, Iraq.

The suit being filed today by 104 Democratic House members and three senators is aimed at forcing an end to the escorting operation unless Congress specifically authorizes its continuation or declares war on Iran. Officials participating in the suit conceded, however, that the administration was certain to appeal an adverse ruling by the district court, a process that could take months.

Lowry, chairman of the Democratic Study Group, a research organization of mostly liberal House Democrats that coordinated preparation of the lawsuit, said those bringing the suit were "again hoping that this moves the administration to change the policy" in the Persian Gulf.

Under the War Powers Resolution, the president is required to notify Congress when he has introduced U.S. forces into combat or situations where "imminent involvement in hostilities" is likely. The law requires the president to terminate such operations within 60 days of reporting to Congress unless Congress declares war, authorizes the operation or extends the 60-day deadline.

If the court should rule that the War Powers Resolution does not apply to the Persian Gulf situation, the lawsuit asks that the reflagging of the Kuwaiti tankers be declared illegal. The suit charges that in reflagging the tankers the Reagan administration waived certain safety and inspection provisions of U.S. maritime law that were meant to be bypassed only in conditions "amounting to a military emergency or a state of war."

At the same time, the House Armed Services subcommittee on military personnel and compensation held its first hearing on a bill that would force the Defense Department to pay bonuses to U.S. personnel who have served in the gulf since May 1.

"To not pass this bill is to pretend like the Persian Gulf is more like Lake Michigan than it is a very troubled and dangerous international waters," said Rep. Patricia Schroeder (D-Colo.), who introduced the measure. "Danger pay is only $110 a month. It hardly compensates our brave sailors for the dangers they face patrolling the gulf."

Pentagon officials told the subcommittee current law provides that field commanders decide whether their troops are in enough danger to warrant the special pay. Officials said that only the captain of the USS Stark, which suffered a missile attack by an Iraqi pilot May 17 that left 37 sailors dead, has ordered bonus compensation for his crew and officers in the Persian Gulf.

When Shultz was asked by reporters yesterday whether the reflagging could lead the United States deeper into the threat of war, he said, "I don't think there's any prospect at all that we'll be drawn into a shooting war . . . . Our presence in the gulf is not provocative. We are there to deter acts of aggression against perfectly legitimate shipping by countries that are neutral . . . . Obviously if we are attacked, we will have to see what actions we'll take."

Assistant Secretary of State Richard W. Murphy said that Iranian-instigated terrorist attacks as a result of the Persian Gulf operations are a possibility and that the West should be "very much on the alert." Murphy made the remark in a television interview broadcast in Europe and Israel yesterday.

Pentagon sources said yesterday that at least four U.S. warships would be involved in the second escorting operation. Sources also said the Bridgeton, damaged when it hit a mine during the first escort July 24, is scheduled to be escorted out of the gulf after the convoy of the three newly reflagged ships is completed.

Administration officials have said they are considering stronger restrictions on commercial trade with Iran. Total U.S. export to Iran was about $13 million in the first five months of this year.

Staff writers John M. Goshko and Mark Lawrence contributed to this report.