The head of the Japan Coast Guard's Okinawa regional headquarters handed a letter of apology to the captain of a Taiwanese fishing boat that sank in a June 10 collision with a JCG patrol ship, coast guard officials in Tokyo said Friday.

The letter was sent to skipper Ho Hung-yi in response to an outcry from Taiwan for a clear apology, the JCG said.

Part of the letter quoted by a JCG official over the phone read: "(We) apologize from the bottom of our heart."

Nasu Hideo, commander of the 11th Regional Coast Guard Headquarters, told a news conference June 15 that the accident was "regrettable."

But the Taiwanese government called for a less ambiguous apology, reflecting the prevailing public anger in Taiwan over the incident.

"(Nasu) used the word 'regrettable' at the news conference as an expression of apology, but it seemed the (sense of remorse) was not fully conveyed to the (Taiwanese) captain," said a spokesman of the JCG's headquarters in Tokyo.

"So we handed the letter to the captain today to deliver our (apology)," the official said.

On June 10, the JCG patrol vessel Koshiki collided with a Taiwanese sport fishing boat near Uotsuri Island, part of the disputed, uninhabited, Japan-controlled Senkaku Islands in the East China Sea.

All 16 people aboard the boat were rescued by the Koshiki but the sinking sparked anger in Taiwan.