Authorities detained the captain of an Italian freighter and accused him of ramming a Greek cruise ship in an accident that killed two Greek seamen, injured 54 passengers and left two people missing.

Italian officials on Saturday denied the Greek allegation and said the freighter was at a standstill before the crash.Officials had reported a British teenager was missing and feared dead after Friday's accident, and on Saturday sponsors of the tour of British students said a teacher also could not be accounted for.

Schools Abroad, the London-based organizer of the trip, identified the missing student as Vivien Barley, 14, of Sutton Confield, England, and the teacher as Bernard Butt from the T.P. Riley Community in Walsall, England.

The collision involved the freighter Adige and the 6,300-ton Jupiter, which was carrying 486 British students and teachers. Most of the schoolchildren arrived in London Saturday for tearful reunions with their families.

The crash tore a gaping hole in the port side of the Jupiter, which sank less than a mile from shore. All others aboard the Jupiter were rescued, and no injuries were reported from the Adige.

Italian officials denied Greek claims that the Adige was at fault.

"The responsibility for the collision is that of the captain of the Adige, who, through criminal negligence, threw his ship into the left side of the Jupiter," said Greece's merchant marine minister, Evangelos Yannopoulos.

The Adige, a container ship owned by Sicula Oceanica SPA, Siosa Line, of Palermo, Sicily, ignored warnings from the Jupiter's skipper as it was manuevering to dock, said Spyros Mavrikis, a spokesman for Epirotiki Lines, the Jupiter's owner.

Premier Andreas Papandreou, returning to Athens Saturday after undergoing heart surgery in London, told reporters before his departure that "it was a question of the captain not knowing what he was doing."

But Adige Capt. Flavio Caminale, being held in the port city of Piraeus on manslaughter charges, said the Greek ship was to blame.

"We were stopped outside the Piraeus port, waiting for the pilot so we could go in," Caminale said in a telephone interview with Italy's RAI television network. "The pilot was coming towards me. At a certain point, I saw the cruise ship leaving port. . . .

"Probably the wind pushed it, and I found it coming upon me. So when I realized after a few seconds that this ship was coming at me, I ordered the engines in reverse . . . and, at the last moment, when he (the cruise ship) saw that he couldn't pass, he violently tacked to starboard. And in so turning himself, he struck my prow."

In Rome, Italy's Merchant Marine Ministry said the Adige "had been at a standstill for 10 minutes when Capt. Caminale spotted the Jupiter leaving port and realized promptly that it was on a collision course.

"The captain of the Italian ship immediately ordered its engines to reverse direction," the communique said.

There was not enough time for the order to be carried out, said 2nd Lt. Enrico Costantini at the ministry's operations center.

Asked if the Greek ship had struck the Italian vessel, he said, "I think so. That is what it appears at this moment."

Students and teachers were flown back to Britain Saturday aboard four chartered jets. Some were still wrapped in blankets and many wept as they boarded the jets.