Elite fighters from the Counter-Terrorism Service raided a headquarters in southern Baghdad used by Kataeb Hezbollah, a pro-Iran faction also identified as Brigade 45 of the Hashed al-Shaabi military force.

"Based on intelligence information, a CTS unit raided a base used by Brigade 45, seizing three rocket launchers and arresting 13 fighters," one of the officials said.

Since October, nearly three dozen attacks have targeted American interests in Iraq, including a range of military bases, the US embassy in Baghdad and US oil companies.

They have killed Iraqi, US and UK military personnel.

The US has blamed Kataeb Hezbollah for the attacks and has retaliated twice, in both cases after rockets killed US military personnel stationed at Iraqi bases.

Washington has pressured Baghdad to take tougher action against the group, and Thursday's late-night raid is the first of its kind.

Kataeb Hezbollah (KH) is a powerful faction within the Hashed al-Shaabi, a network of armed groups that have been integrated into the Iraqi security forces.

KH are known to be close to Iran and deeply opposed to the US presence in the region.

The CTS, meanwhile, was set up by US occupation forces following the 2003 invasion that toppled Saddam Hussein and is largely seen as a force friendly to Washington.

Its commander, Abdulwahab al-Saadi, was appointed last month by new prime minister Mustafa al-Kadhemi, whom Washington considers an ally.

Under Kadhemi, Iraq and the US launched a strategic dialogue earlier this month to reset the bilateral relationship.

The start of the talks coincided with a significant spike in rocket attacks, with six incidents targeting American installations over the course of two weeks.

The escalation shattered the period of relative calm that had settled in after particularly high tensions between Iran and the US spilt over into Iraq.

Iran is Iraq's influential eastern neighbour and holds considerable sway over political and military actors in Baghdad.