NEW YORK, US - The father of an Afghan-born airport shuttle driver accused of plotting an al Qaeda-inspired bomb attack on New York City pleaded not guilty on Tuesday to charges of conspiring to alter, destroy and conceal evidence.

Mohammed Wali Zazi, 53, was transferred on Tuesday from Denver to New York and appeared in Brooklyn federal court, said Robert Nardoza, spokesman for the U.S. Attorney's Office in Brooklyn.

Zazi, who was arrested in Denver in January, appeared before Chief Magistrate Judge Steven Gold and was ordered held on a permanent order of detention, Nardoza said.

He is accused of conspiring to alter, destroy and conceal objects, including liquid chemicals, "with the intent to impair the objects' integrity and availability for use in an official proceeding."

If convicted of the charge he faces a maximum sentence of 20 years in prison.

His son, Najibullah Zazi, 24, a former coffee vendor who had moved to Colorado, was arrested in September and accused of plotting a bomb attack in New York City on the anniversary of the Sept. 11 attacks.

He has pleaded not guilty.

U.S. Attorney General Eric Holder called it one of the most serious security threats to the United States since the hijacked airliner attacks of Sept. 11, 2001.

A New York imam and two men who attended a New York City high school with Zazi also have been charged. All have pleaded not guilty.

According to The New York Times, Najibullah Zazi's uncle, Naqib Jaji, 38, has also been arraigned in Brooklyn federal court, and is reported to have pleaded not guilty to one felony count. --REUTERS