Afghan men walk at the scene where a Swedish journalist was fatally shot in Kabul. (Rahmat Gul/AP)

KABUL – A more radical militant group has claimed responsibility for killing a Swedish journalist in a brazen raid in the Afghan capital.

The slaying on Tuesday of 52-year-old Nils Horner, who also held British citizenship in Kabul’s diplomatic enclave, has sent a new shock wave for foreigners living there.

While Afghans are still probing the motive and scrambling to find the two culprits who fled right after the attack, a militant group calling itself Fidayee Front of Afghanistan’s Islamic Movement said it carried out the killing.

The group, which according to some Afghans has been operating separately from the Taliban insurgents led by Mullah Mohammad Omar, was formed in recent years. The group said it killed the journalist because it believed he was a spy for the British M.I.6.

“Mujahideen targeted Nils Horner. Nils Horner was killed in this attack. He was not a journalist. He was a spy of (M.I.6), he was a special worker of (M.I.6),” a statement on the group’s website quoted its spokesman Qari Hamza as saying.

Swedish journalist Nils Horner, photographed in Stockholm in August. (Mattias Ahlm/Sveriges Radio via AP)

The group claims loyalty to Mullah Dadullah, a notorious Taliban commander killed in 2007.

It has also claimed responsibility for killing a former Taliban minister, Mullah Arsala Rahmani, in 2012 in Kabul.

Rahmani, who lived under government protection in Kabul, was viewed as a potential intermediary in stalled peace talks between the government and the Taliban led by Mullah Omar and other insurgents.

On Wednesday, an official for Afghanistan’s main intelligence agency said it recently foiled a major planned attack in Kabul by the Dadullah group.