Men on a motorbike have shot and killed a Saudi diplomat as he was driving in Pakistan's largest city, just days after two hand grenades were tossed at the consulate building, police in Karachi said.
The motive for the attack was not clear, but it comes against a backdrop of tension between Islam's Sunni and Shiite branches, both in the Middle East and in Pakistan.
Saudi Arabia has funded hardline Sunni groups in Pakistan for years, angering its minority Shiites. Meanwhile, Iran has channelled money to Shiite groups, and in the 1980 and 1990s the country was the scene of an effective proxy war between the two countries, with Karachi a particularly bloody battleground.
The attack took place not far from the consulate building. The diplomat - who was driving his vehicle alone - was perhaps going to work having left his home, said police officer Zameer Husain Abbasi. He said a 9mm pistol was used in the assault.
The victim was a member of the "security staff" at the consulate, said Iqbal Mehmood, Karachi's deputy inspector of police. He said the shooting appeared to be linked to last week's grenade attack on the mission, which caused some damage but no injuries.
Officials at the Saudi mission were not immediately available for comment.
Karachi is a violent city of 18 million people, a cauldron of ethnic, sectarian and political tensions. Pakistan's alliance with Sunni rulers in the Middle East has come under the spotlight since the uprisings there this year.
A company with strong links to the country's army announced it was sending 1,000 Pakistanis to Sunni-led Bahrain to help its security forces put down an uprising by its majority Shiites, angering Pakistani Shiites.
The attacks on the consulate and its staff also follow the May 2 US raid in north west Pakistan that killed Osama bin Laden, the Saudi-born chief of the al Qaida terrorist network.
Saudi Arabia stripped bin Laden of citizenship and has fought al Qaida, but money from some of its citizens is believed to help bankroll the terrorist network, which have carried out scores of attacks inside Pakistan over the last 10 years.