Story highlights Princess Cruises is investigating what happened after passengers raised the alert

One of its cruise ships is accused of failing to come to the aid of the stricken vessel

Cruise line: A communication breakdown meant the captain wasn't told of the boat

A sole survivor, Adrian Vasquez, 18, was eventually rescued after 28 days adrift

An American cruise line has said it "deeply regrets" the deaths of two Panamanian fishermen amid claims that one of its cruise ships failed to help their stranded boat.

Princess Cruises said passengers on the Star Princess apparently alerted a crew member to the disabled fishing boat in March, but initial indications are that the captain was never told.

Later that month, the Ecuadorian navy rescued the only survivor of what was meant to be an overnight fishing trip, 18-year-old Adrian Vasquez, after 28 days adrift.

Since then, pressure has grown on the cruise line from local and international media to explain why it failed to help.

Broadcaster NPR first reported the claim by three passengers, all bird-watchers, that they had spotted the castaways and told cruise ship staff but had seen no action taken.

A reporter with the Panama-Guide.com website confirmed with Vasquez that he and his two friends, who at that point were still alive, had tried to attract the attention of the passing cruise ship.

Princess Cruises "deeply regrets that two Panamanian men perished at sea," its statement Thursday said.

"The preliminary results of our investigation have shown that there appeared to be a breakdown in communication in relaying the passenger's concern. Neither Captain Edward Perrin nor the officer of the watch were notified," it said.

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"Understandably, Captain Perrin is devastated that he is being accused of knowingly turning his back on people in distress."

If Perrin had received the information, he would have been able to respond appropriately, the company said.

"We all understand that it is our responsibility and also the law of the sea to provide assistance to any vessel in distress, and it is not an uncommon occurrence for our ships to be involved in a rescue at sea," it said.

Its ships have been involved in more than 30 rescues in the past decade, Princess Cruises added.

The story of Vasquez's miraculous survival gained international coverage when he was picked up north of the Galápagos Islands.

The alert was first raised by Vasquez's parents after he and his two friends, Oropeces Betancourt, 24, and Fernando Osorio, 16, failed to return as expected to the town of Rio Hato, Panama.

Local fishermen and then the Panamanian navy joined the search, sending ships and airplanes to look for the trio, to no avail.

For nearly a month, their fate remained a mystery. But on March 21, fishermen spotted the boat, named the Fifty Cents, adrift nearly 600 miles from where it had launched.

After being alerted by the fishermen, the Ecuadorian navy rescued Vazquez.

Rear Adm. Freddy Garcia Calle said Vasquez showed "severe signs of dehydration and lack of nutrition" when he was found.

He said the survivor had thrown his friends' bodies into the ocean "because they had become badly decomposed."

Vasquez's mother, Nilsa de la Cruz, told CNN last month that she was overjoyed to have her son back.

"After 28 days of anguish, after praying to God that he be found alive ... this is indeed a miracle," de la Cruz said.

She said her son told her the February 24 fishing trip had started out well. The three caught plenty of fish. But the boat's engine died without warning and, with no tools and scant navigational experience, there was little the trio could do, de la Cruz told CNN.

Soon, currents had swept their boat out into the Pacific, far from the coast. De la Cruz said the three ate raw fish and drank rainwater.

They had already been adrift for two weeks when passengers on the Star Princess apparently spotted their tiny boat as the fishermen waved for help.