Security services in Denmark said Tuesday further anti-terror arrests could be made after US authorities charged two men over a plot to attack a Danish newspaper that published controversial cartoons of the Prophet Mohammed.

- We can't rule out that more persons will be arrested and prosecuted for the planning of terrorist attacks in Denmark - Jakob Scharf, the head of the Danish Security and Intelligence service, told reporters in Copenhagen.

- We will continue to cooperate very closely with the FBI and with security services in a number of fellow countries in order to crack the threat - he added.

Officials in the US announced the arrest of two men on Tuesday. Scharf said they were involved in - very serious planning of comprehensive attacks in Copenhagen and in Denmark.-

The pair were identified as David Coleman Headley, 49, a US citizen, and Tahawwur Hussain Rana, 48, a native of Pakistan with Canadian citizenship.

Headley was charged with one count of conspiracy to commit terrorist acts involving murder and maiming outside the United States, and one count of conspiracy to provide material support to that overseas terrorism conspiracy.

Rana was charged with one count of conspiracy to provide material support "to a foreign terrorism conspiracy that involved Headley, and at least three other specific individuals in Pakistan," the US Justice Department said.

The men were arrested in Chicago, Illinois, on October 3 and 18.

Video tapes showing the offices of the popular daily Jyllands-Posten in Copenhagen were among the objects found by investigators -- the newspaper triggered an outrage in the Muslim world by publishing 12 cartoons of Prophet Mohammed in 2005.

According to the Danish security services, who collaborated with the FBI, the two suspects visited Denmark twice, for the last time in July 2009, to determine the targets of their attacks.