Two European aid workers have been kidnapped overnight in Pakistan's central shrine city of Multan, local police say.

Friday's report of the abduction of a Dutch, originally thought to be German, and Italian aid worker by masked armed men brings the total number of Westerners kidnapped to six since July.

"Three gunmen barged into a house and abducted an Italian and a German national at gunpoint on Thursday evening," Aamir Zulfiqar Khan, a city police officer, told the AFP news agency via telephone.

Initial reports had identified one of the aid workers as German, but Al Jazeera sources say he is in fact Dutch.

Police do not yet have a motive for the abduction of the two men working for German NGO Welthungerlife WHH, a non-governmental organisation that is helping the victims of the floods of 2010. The identity of the kidnappers also remains unclear.

A local security official told the AFP that the kidnappers had pistol-whipped a private security guard, then snatched the aid workers, but left behind a Western woman in the house that the group rented.

"The woman was unable to identify the kidnappers because they covered their faces with masks," the official said on condition of anonymity because he was not authorised to speak to the media.

There was no claim of responsibility for the abduction 400 kilometres southwest of the capital Islamabad.

Kidnapping confirmed

The Italian foreign ministry confirmed that one of its citizens had been kidnapped in Punjab, saying it was in "permanent contact" with the man's family and had activated its crisis unit, but released no further details in a call for discretion.

Kidnappings are common in parts of Pakistan. Criminals snatch foreigners and locals for ransom, sometimes selling their hostages to Taliban and al-Qaeda-linked groups.

Multan, the largest city in central Punjab province, is known for Sufi shrines, mosques, and historic tombs. It had not previously been considered dangerous for Westerners.

Earlier this month, armed men kidnapped a British man working for the International Committee of the Red Cross (ICRC) in Quetta.

Last August, an American development director, Warren Weinstein, 70, was snatched from his home in Lahore, and in July a Swiss couple were kidnapped while driving through Balochistan.

The Taliban claim to be holding the Swiss and videos have been released of the couple in captivity.

Ayman al-Zawahiri, the al-Qaeda leader, also claims to be holding Weinstein, but has released no proof of life.