Danish police arrested eight young Muslims in pre-dawn raids on Tuesday on suspicion of plotting a bomb attack and having links with al Qaeda.
Jakob Scharf, director of the Danish police's Security Intelligence Service, did not say what the alleged target was or which country it was in.
But he said it was the first such direct al Qaeda connection discovered in Denmark and that Danish intelligence had cooperated with unnamed foreign security services during an investigation that lasted several months.
"These are militant Islamists with connections to high-ranking members of al Qaeda," Scharf told a news conference. "We believe this was a serious situation."
Terror experts said Denmark was on the radar for extremists because of its military involvement in Iraq and Afghanistan and a crisis sparked last year when cartoons lampooning the Prophet Mohammad were published in a Danish newspaper.
The Muslims arrested ranged from 19 to 29 years old. They came from Afghan, Pakistani, Somali and Turkish backgrounds and six were Danish citizens, Scharf said.
"Our investigation has shown that some of the suspects had acquired materials to make explosives," he said.
He did not say whether any explosives had been found but said important evidence had been discovered in the raids in central Copenhagen and its suburbs.
Scharf said the arrests underlined the intelligence service's belief that individuals and groups of people in Denmark had the will and capacity to launch attacks and that al Qaeda had recovered the strength to launch attacks in Europe.
He said two of the suspects -- the ones believed to be the main players -- would soon face a custody hearing, and the others would most likely be released after questioning.
Suspects can be remanded in custody under preliminary charges for months in Denmark.
The arrests were the latest in a series of cases Danish authorities have pursued under anti-terrorism laws passed after the Sept. 11, 2001, attacks in the United States.
A Copenhagen court sentenced a Danish Muslim youth to seven years in prison in February for planning an attack in Europe, but cleared three others. Prosecutors are seeking a retrial in one of the three acquittals.
Four other men are awaiting trial on charges of plotting a bomb attack in the Nordic country, which has troops in Afghanistan and recently scaled down its military presence in Iraq to a small contingent.
