FUJAYRAH, UNITED ARAB EMIRATES, AUG. 20 -- A convoy of three reflagged Kuwaiti tankers escorted by U.S. Navy ships stalled in the Persian Gulf today near Bahrain as low visibility and choppy seas hampered mine-searching operations.

The ships reportedly dropped anchor about halfway through the gulf to Kuwait, just as they were about to enter one of the most dangerous portions of its journey.

An earlier convoy of U.S.-flagged vessels stalled at about the same point after mines were discovered in the waters ahead. Due to shallow waters and an "exclusion zone" declared by Iran that is apparently being observed by other countries, large ships such as tankers stick to very narrow channels as they make their way through the northern part of the gulf. These channels are believed to be particularly vulnerable to mines.

There was no suggestion today that the current pause is a result of the discovery of any mines.

{In The Hague, Dutch Foreign Minister Hans van den Broek said after a meeting of officials of the Western European Union that his country is willing in principle to send mine sweepers to the Persian Gulf, Reuter reported. In the past the Netherlands has said it would only be willing to consider sending a naval force in conjunction with the United Nations, but the Dutch official said, "We feel the chances of an early U.N. solution (are) fading and that is why we are now turning to a European forum." British and French mine sweepers are on their way to the area.}

As the American-escorted convoy waited to resume its voyage, shipping sources noted with alarm the second incident in two days in which Iranian vessels fired at or near a ship that failed to heed an initial warning to stop.

A 5,597-ton Yugoslav vessel, the Bribir, finally was forced to halt in the southern part of the gulf when an Iranian frigate fired warning shots across its bow, according to shipping sources. The vessel then was boarded and searched by Iranian marines, apparently seeking war materiel destined for Iraq.

The Norwegian-operated tanker Osco Sierra suffered minor damage the day before when gunboats identified as Iranian fired at it in the Strait of Hormuz near the Gulf of Oman. Iran has denied the attack.

Shipping sources at this normally busy port on the Gulf of Oman said the Osco Sierra incident had been preceded by a similar challenge to a vessel off Fujayrah, indicating that Iranian vessels are expanding the area in which they perform stop-and-search operations.

A Dubai-based journalist reported last week that a U.S. Navy vessel apparently intervened in a similar incident involving a tanker, effectively chasing away the Iranian challenger. It was unclear whether these were separate incidents.

The combination of increased searches and mines that have been found off Fujayrah has thrown a chill into the operations of this port, which once handled a major portion of resupply missions to tankers involved in the Persian Gulf oil trade.

Following the sinking of a mine resupply ship last week, however, waters near Fujayrah have been declared a danger zone and the only resupply missions from here have been by helicopter, with the exception of small companies still willing to risk the trip.

The charges for maritime insurance in the area have increased dramatically.

"No one ever paid much attention to the danger because no one ever believed it would come their way," said an experienced shipping source, describing the unease that has settled over the port area.

Many tankers now are believed to have moved away from Fujayrah to ports north and south of it on the Gulf of Oman. The harbor master at the nearby port of Khor Fakkan reportedly said today that he had "never seen so many ships" anchored in deep waters off the small container port.

Nevertheless, there appears to be uncertainty in the tanker trade about where ships will stop as they make their way to and from the gulf or await new contracts.

Fujayrah has been handling the bulk of this traffic and officials appear hopeful that conditions will become calm enough for it to resume that role.

The mine warnings did not keep away the President Pierce, a large container vessel belonging to the U.S.-owned President Line, which arrived at Fujayrah port at midday today.