Three Norwegians accused of plotting, with al Qaeda's help, to bomb a Danish newspaper for printing cartoons of Islam's Prophet Mohammad, pleaded not guilty to the charges in court on Tuesday.

The alleged ringleader, Mikael Davud, learned how to use explosives at an al Qaeda camp in Pakistan and made an agreement with the terror organisation to blow up Denmark's daily Jyllands-Posten, prosecutor Geir Evanger said on the first day of the trial.

The three acquired bomb ingredients like hydrogen peroxide and acetone while two of them may also have planned to kill a Danish cartoonist who had drawn the Prophet with a bomb in his turban, Evanger said in his opening statement.

This is a ground-breaking case in Norway, Davud's attorney, Arild Karl Humlen, told Reuters.

It is the first full-scale test of new (Norwegian) terror laws and the first time they (the prosecutors) are linking a terror conspiracy to an international organisation.

Jyllands-Posten was the first of several European publications to print cartoons lampooning the Prophet in late 2005 and early 2006, sparking violent protests in the Middle East and Africa and a widespread debate about press freedom.

As recently as November 2, a firebomb attack gutted the headquarters of French satirical weekly Charlie Hebdo after it put an image of the Prophet on its cover.

Davud, a Norwegian citizen of Chinese Uigur origin, trained with al Qaeda in Pakistan from 2008 to 2009 and remained in contact with the group until the trio's arrest in July 2010, the prosecutor said.

Davud has used e-mail to correspond with them (al Qaeda) and he has talked to them, cooperating about the target, Evanger told Reuters.

Weapons manuals, bomb-making instructions and pro-al Qaeda propaganda were found on his computer in Norway, Evanger said.

Davud's attorney told Reuters his client insists the training he received was in Iran and had nothing to do with al Qaeda.

He says he went to Iran to learn to make a bomb that he would use at some point in his life to attract interest to what the Chinese are doing to the Uigur population, Humlen said.

Some Uigurs in China's easternmost province, most of them Muslim, have agitated for a separate state or more autonomy.

After his arrest, Davud, 40, admitted he intended to attack Chinese interests like the Chinese embassy in Oslo, police said last year, but he is charged only with plotting to bomb the Danish newspaper.

Shawan Sadek Saeed Bujak, a 38-year-old Iraqi Kurd with Norwegian residency, joined the newspaper plot in 2009 and stored explosive chemicals at his home, the prosecutor said.

He and Davud have been in custody since the arrests.

The third defendant, a 33-year-old native Uzbek national named David Jakobsen, was released last year proclaiming his innocence but remained under investigation.

According to Evanger, Jakobsen delivered hydrogen peroxide to Davud several times. Evanger said Jakobsen's participation lasted until he contacted police in November 2009, after which he assisted the investigation.

Evanger said the trial, expected to last six weeks, would include surveillance tapes and testimony from a U.S. investigator with knowledge of the al Qaeda contacts Davud allegedly maintained.