NEW YORK (AFP) - Osama bin Laden's son-in-law, accused of terror related charges, on Tuesday defended his choice of lawyer, a decision that the judge in the case has called a "mistake."

"In life every matter has its own risks and I'm ready to take this," Suleiman Abu Ghaith, said at a hearing at the federal court in Manhattan.

Abu Ghaith, who appeared in a video Sept 12, 2001 with the Al-Qaeda leader claiming responsibility for the deadly 9/11 strikes on US targets, is accused of conspiring to kill Americans. He has pleaded not guilty.

Last week, he announced he had dropped his court-appointed attorneys in favour of Stanley Cohen, who has experience defending Islamists, but is, himself, the target of two tax-related court cases.

Federal Judge Lewis Kaplan said choosing Mr Cohen was "a mistake. It's against your interests." Because of the charges against Mr Cohen, the lawyer risked not being allowed access to certain classified documents, he said.

Judge Kaplan had already told the defendant at the previous hearing that there could be a potential conflict of interest if Cohen were to be found guilty and jailed during his case - and that that could leave him with no defense.

But Abu Ghaith insisted he would not be swayed.

"I understood the possible problems that could happen. I'm comfortable that they will remain representing me in this case," he said of his legal team.

Judge Kaplan has set a Jan 7, 2014 date to start the trial of the former Al-Qaeda spokesman. The 47-year-old Kuwaiti, married to Bin Laden's daughter Fatima, could be sentenced to life in prison if he is convicted.