A Soviet seaman who twice jumped from his ship into the Mississippi River near New Orleans in an apparent attempt to defect assured U.S. officials yesterday that he wanted to go home and, after signing a statement to that effect, returned to the vessel.

"The United States government considers this matter closed," the State Department said last night at the conclusion of a lengthy statement recounting its efforts since Friday to ensure that the sailor, Miroslav Medvid, had been given every opportunity to gain asylum.

The length and minute detail of the statement underscored administration awareness of the case's potential sensitivity.

According to the department's account, Medvid, removed Monday evening from the Soviet grain freighter, Marshal Konev, repeatedly insisted in interviews Monday and yesterday after a night of rest ashore that he wished to return to the Soviet Union.

He also signed a Russian-language statement reiterating that desire.

However, there was no explanation of what caused Medvid to precipitate the incident by leaping from the freighter last Thursday. Also left unanswered by the official statement was whether federal authorities initially mishandled the case by having Medvid returned to the ship under orders from the U.S. Border Patrol.

A State Department official in New Orleans, speaking on condition that he not be identified, told reporters that the patrol had not followed well-established procedures for dealing with such cases.

However, Duke Austin, a spokesman for the Immigration and Naturalization Service, which oversees the patrol, said that, while further review would be required, his agency has no immediate grounds for believing that the patrol had not acted correctly.

Austin said patrol agents asked Medvid several times through an interpreter whether he wanted asylum and received a negative answer. Austin added: "There is some perception that we carried this sailor kicking and screaming back to the ship, which we did not."

However, witnesses to the incident said that, when the Border Patrol tried to return Medvid to his ship Thursday, he jumped from a launch and swam to shore. He finally was put back on the freighter Friday.

The State Department chronology picked up the story Friday when it said the department learned of the situation. It said various U.S. officials were aboard the ship from then until Monday evening when Soviet Embassy officials acceded to U.S. insistence that Medvid be interviewed in a "non-threatening environment free from coercion."

An initial interview Monday night on the Coast Guard buoy tender Salvia was broken off when Medvid became nauseated. After he rested, the interview was resumed, and he reiterated to U.S. officials that he was not seeking to defect. He then was brought ashore to a U.S. naval facility for a night's rest.

Yesterday, after examination by an Air Force psychiatrist, he again stated his wish to go home. U.S. officials at the scene were instructed by the White House and the State and Justice departments to ask Medvid if he would confirm this wish in writing.

After he did so, he was released to the Marshal Konev, which now is expected to return to the Soviet Union. U.S. authorities had been preventing the ship from leaving Belle Chasse, La.

The first word of Medvid's decision came from Soviet Ambassador Anatoliy F. Dobrynin. "It's settled. He's coming home," Dobrynin told reporters as he left the State Department after an unscheduled hour-long meeting with Secretary of State George P. Shultz.

Dobrynin said Medvid's case had not figured in the meeting, whose purpose was to discuss Shultz's trip to Moscow this weekend.