US authorities helped Danish security officials locate the terror suspects in an alleged bombing plot unearthed this month through an electronic intercept from Pakistan, where one of the men had received training at an al-Qaeda camp.
The method was similar to that adopted during arrests of some suspects in a bombing plot in Germany, a media report on Monday said quoting intelligence officials in Washington.
One of the men in the Danish case received instruction within the past 12 months in explosives, surveillance and other techniques at a terrorist training camp in Pakistan near the border with Afghanistan, The New York Times quoted officials as saying.
While much of the world's attention was focused on the arrests that took place the same day in Germany but were announced a day later, intelligence officials in Denmark and in Washington were quoted as saying that at least one suspect in the Danish group had direct ties to leading figures in Al Qaeda which has regrouped in northwestern Pakistan.
"What's coming from this is that they are now able to give military and terrorist training and able to plan and steer specific operations in Europe," Jakob Scharf, the Danish intelligence chief, told the Times, adding "al-Qaeda is back."
Scharf, the paper said, drew a clear distinction between independent or loosely affiliated groups drawing inspiration from al-Qaeda's ideology and specific control of plans for attack, saying the Danish bomb plot was clearly the latter.
"I'm not indicating a direct phone line to Osama bin Laden," he said, but leading members are able to "direct operations" outside of Afghanistan and Pakistan.
This was the first time officials here have linked an operation in Denmark to the group that masterminded the terrorist attacks of September 11, 2001 on the US, it said.
Of the eight men arrested, the authorities quickly released six of them, fueling skepticism about the strength of the case and the government's ability to turn arrests into convictions, the report said.
With a population of 5.5 million, Denmark has a disproportionately large target on jihadist Web sites. Not only did Denmark achieve infamy across the Muslim world for the publication of the blasphemous cartoons, which incited violent and even deadly protests across the world.