(CNN) -- Norwegian authorities announced the arrests of three suspects Thursday in connection with an ongoing investigation into terrorist plots in New York and the United Kingdom.

Their apprehension was made possible through international cooperation, including information from U.S. authorities, they said.

The suspects had been under surveillance for several months, the Norwegian authorities said.

The three are suspected of plotting terrorist attacks and having connections to al Qaeda, the Norwegian prime minister's office said earlier.

All three of the suspects are in their 30s and of foreign descent, the Norwegian Police Security Service said. One is a Norwegian citizen and the other two are permanent residents.

The Norwegian citizen is of Uyghur origin, police said. He went to Norway at the end of the 1990s as a resettlement refugee and obtained citizenship in 2007.

The second is an Iraqi-Kurdish man who went to Norway at the end of the 1990s and was granted a residence permit on humanitarian grounds.

The last man is an Uzbek who went to Norway as an asylum seeker at the beginning of the 2000s. His application for asylum was rejected, but he was later granted a residence permit in Norway based on family reunification, police said.

The ethnic Uyghur and the Uzbek were arrested in Oslo, Norway, the prime minister's office said.

The Iraqi citizen was arrested Thursday morning in the western German city of Duisburg, the general prosecutor's office in Frankfurt said. The office said officials there are now working with Norwegian authorities on his extradition.

Police said they had "sufficient control" of all three suspects while they were under surveillance and that the public was never in any danger.

Authorities had considered arresting the men before now, but they decided to apprehend them Thursday because parts of the case became known in the media.

"This would result in a considerable risk of destruction of evidence and evasion in the further investigation of the case," the police service said. "Hence, (we) chose to apprehend the individuals today."

The police service said any groups in Norway that may constitute a threat to national security are small and primarily involved in supporting activities abroad, so Thursday's arrests will not change the current threat level in the country, which remains low.

CNN's Paula Newton and Stephanie Halasz contributed to this report.