Gen. Hudson Austin, the leader of the short-lived Revolutionary Military Council that was toppled in Grenada last week, has been arrested by U.S. soldiers, according to a spokesman for the Barbados Defense Ministry.

In a statement released late tonight on behalf of the Caribbean and U.S. joint task force, the defense spokesman said: "Gen. Hudson Austin was captured at 2:30 p.m. in a private home in Wesper Hall by troops of the 82d Airborne Divison." The spokesman said that the town is six miles east of Point Salines, where a Cuban-built airstrip is serving as the main staging area for the U.S. forces that landed on the small island Tuesday. President Reagan said the invasion was to protect U.S. citizens and prevent the spread of Cuban and Soviet influence in the Caribbean.

The capture of Austin, a Marxist, meant that virtually all the coup's leaders have been detained. Saturday marines captured deputy prime minister Bernard Coard and two other key supporters of Austin's government.

Like Coard and the two others, Austin today was flown by helicopter to the USS Guam off the Grenadan coast. The defense spokesman said he was "a prisoner of the U.S. forces."

He added that details received "indicate that no hostages were involved." Saturday U.S. task force commander Vice Adm. Joseph Metcalf III told reporters in Grenada that the U.S. forces believed reports on the island that Austin was holed up with two "not American" hostages.

In Washington the Pentagon confirmed that a man fitting the description of Gen. Hudson Austin was taken into custody. Austin became leader of the Military Revolutionary Council after prime minister Maurice Bishop, also a Marxist, was killed Oct. 19 by troops under Austin's command.

Maj. Bob Shields, a Defense Department spokesman, stopped short of confirming reports of Austin's capture, but said: "We have information that units from the 82d Airborne Division during operations in Grenada have captured and detained an individual who claims he is Gen. Austin, fits the description of Gen. Austin and was carrying identification to that effect."

Earlier Jenkins had visited Grenada and filed this report after returning to Barbados:

U.S. Marines who had been occupying the quaint seaside capital of St. George's since shortly after their landing Tuesday began to thin out their forces today for redeployment in Beirut. The United States, meanwhile, opened a new embassy in Grenada.

The first U.S. Embassy on Grenada since the island nation achieved independence from Britain in 1974 became a reality this morning when the American flag was run up over the Ross Point Inn, a former resort hotel rented by the U.S. government. Ambassador-designate Charles Anthony Gillespie, until now deputy assistant secretary of state for Caribbean affairs, flew here from neighboring Barbados this morning to hold his first staff meeting in a hotel restaurant pavilion.

"Though technically perhaps there cannot officially be an embassy until it is formally accredited to the constituted government of Grenada," an embassy spokesman said, "the embassy here is already a reality." The spokesman added it would have a staff of between 20 and 30 people.

As the embassy began functioning on a promontory overlooking St. George's harbor, the Marine contingents of the 2d Battalion 8th Marines based around the capital's cricket grounds at Queen's Park were packing up for departure north to the international airport at Pearls where they had landed Tuesday when the two-pronged U.S. invasion of the island began.

"You can say we are winding down and some of our men are already moving out," said a Marine spokesman, Capt. Dean Chamberlain.

Chamberlain said that the marines in St. George's and Pearls would be replaced by elements of the 82d Airborne Division who are headquartered at the Cuban-built airstrip on the southern tip of the island at Point Salines. U.S. military officials from the 15,000-man U.S. joint task force on Grenada and offshore have said U.S. troops would not be withdrawn from the island until security is reestablished and some form of civilian authority to govern Grenada is created.

There were signs today that progress on both those fronts might be moving quicker than had been expected a couple of days ago when U.S. forces were conducting operations against snipers and there was a vacuum of political power on the island following the collapse of the government.

Today proved to be the quietest day of military operations since the landings Tuesday. U.S. military spokesmen reported no contact with resistance forces and for the first time in six days the cloud-dotted blue skies over Grenada were free of swooping carrier-based fighter-bombers and slow circling gunships.

On the political front, Paul Scoon, the island's governor general, was reported to have begun to appoint a council of "persons of integrity and ability" to administer the country as an interim government until elections can be organized.

"Scoon is already making appointments," said Col. Ken Barnes, the Trinidad-born Jamaican commander of the 300-member Caribbean Security Force that has joined the U.S. military on the island to give the massive U.S. landing a multinational character.

"We are going to have a civilian government this week."

As one other sign of normality returning to the Grenada capital, Barnes said that the looting of stores that had plagued the capital nightly last week had come to a halt yesterday.

"A lot of the looting was by people who just wanted food and couldn't resist," Barnes said, revealing that at least 15 persons had been arrested for breaking into locked stores.

Meanwhile Grenada experienced a second foreign invasion of sorts today when more than 125 journalists were allowed to come to the island and wander at will. Until today the U.S. military had tightly controlled media access to Grenada, rigidly limiting visits to restricted pools.

The restriction on visits by journalists was finally reversed today after both houses of Congress passed resolutions yesterday demanding that the controls be lifted.

Along the Carrenage, the wide avenue ringing the harbor, groups of Grenadans gathered to exchange stories in front of such still shuttered shops as the Judi 'n Jeni Boutique and the Hole In The Wall Refreshment House while small boys swam and splashed in the still waters of the inactive harbor. Two young men roller skated along the street as dozens of young couples walked gaily about laughing and talking and looking at patrols of marines.

When a Grenadan youth was asked if any of the marines had yet married Grenadan women, he laughed and said: "No, but some be mighty close."