Shoichi Yukawa, the father of hostage Haruna Yukawa, who has reportedly been slain by the extremist Islamic State group, said Sunday he hopes it is not true but said it is extremely regrettable his son's fate seems to have been sealed.

"My mind went totally blank," Yukawa told reporters at his home in Chiba. "I cannot find any other words."

The father, 74, said he received a phone call from the Foreign Ministry around midnight Saturday telling him his son appeared to have been killed, though it could not be confirmed.

"My heart aches that it has turned out to be like this. I hope it is not my son, but I just feel awful," he said, his voice trembling.

As for journalist Kenji Goto, who was being held alongside his son for a $200 million ransom set as a rebuke to Prime Minister Shinzo Abe, Yukawa said his son held great respect for Goto and said he was a sincere and kind man with courage who acted like his big brother.

"Mr. Goto risked his life to go there (Syria) because he was worried about my son. I feel very bad about this," Yukawa said.

Yukawa said he has had no direct contact with the terrorists.

"I feel the importance of human lives. I want to ask (all parties) to stop fighting."

In a 25-minute group interview, Yukawa repeatedly said he hoped the death of his son was not true and that he would hug him if he ever saw him again.

But he also said: "I am very sorry that (my son) caused trouble for the government and other people. I am grateful for their immense help."