"We couldn't have signed a different report," said psychiatrist Torgeir Husby who along with Synne Sorheim concluded Breivik was suffering from paranoid schizophrenia and was psychotic.

The findings of Husby and Sorheim published in November were questioned by other experts and caused a public outcry. Their diagnosis suggested he was not accountable for his actions and should be held in a secure psychiatric unit if convicted, instead of being sent to prison.

"It would have been an advantage to let him (Breivik) speak more since he is his own worst enemy. As soon as he opens his mouth, people sense something is wrong," Husby told the Oslo District Court.

Husby and Sorheim said Breivik had "adjusted" his behaviour compared to when they interviewed him while he was in custody.

"He is not stupid. He responds to reactions to his views," Husby said.

Sorheim said that among Breivik's delusions they had identified was his "claim that he had the right to determine who would live or die."

Breivik has maintained that 80 percent of conversations in the report were "made up" but Sorheim said they had presented facts "as they were."

Breivik, 33, has confessed to killing 77 people in twin bombing and shooting attacks in July, but has pleaded not guilty.

Early this year, the Oslo District Court ordered a second psychiatric assessment. It was presented shortly before the trial opened in April, and concluded Breivik was accountable for his actions.

Director of Public Prosecutions Tor-Aksel Busch told reporters it was "still open" how the prosecution would argue in its closing statement, which will be made after the second team of psychiatrists testify. The trial is set to run until June 22.

The second report included a three-week observation of Breivik in prison. Husby had no comment when presiding judge Wenche Elizabeth Arntzen asked why the medical staff that observed Breivik had not seen any signs that he suffered from paranoid schizophrenia.