Tongan ferry Princess Ashika, which sank with the loss of 73 lives, was repaired at night to stop people querying its seaworthiness, Tonga's Kele'a newspaper says.
The newspaper report stemmed from a letter written by the head of the Ports Authority to the Tongan prime minister on August 11, six days after the ferry sank.
Authority head Commander Lupeti Vi was said to have claimed the vessel was not fit even to sail from the main wharf to a resort island 1km away, Radio New Zealand International reported.
He should have been informed in writing if there was going to be any welding within the port because it was dangerous, he said.
The vessel was welded in the night -- apparently as a way of hiding just how rusty it was, he said.
Photographs accompanying the letter showed big holes in the ferry.
The letter reportedly warned the prime minister of possible bloodshed if the photographs were made public.
But Cdr Vi said the letter was never meant to be made public.
"I'm not worried about it because what I said on the letter is the truth," he said.
"Whatever the consequences of that, it's up to the people to decide. All I'm telling you is I'm not happy to see that the letter has been published in the paper or the media because the letter was written to the prime minister."
The prime minister declined to comment as the matter was before the Royal Commission.
NZPA