The United States has ordered the evacuation of non-essential staff from its consulate in the northeastern Pakistani city of Lahore due to the threat of attack.

The State Department has also warned US citizens not to travel to Pakistan.

The warning comes two days after the US evacuated some diplomats from Yemen and told its nationals to leave that country immediately.

The US shut nearly two dozen missions across the Middle East after a worldwide alert on 2 August.

It warned its citizens that al-Qaeda may be planning attacks in August, particularly in the Middle East and North Africa.

The Lahore warning noted that "several foreign and indigenous terrorist groups pose a potential danger to US citizens throughout Pakistan".

A US embassy spokeswoman said the closure was due to a specific threat to Lahore and that it was unclear when the consulate would reopen.

It was also unclear if the Lahore announcement was linked to the earlier US closures.

Tensions have also risen this week with Pakistan's neighbour India over the disputed territory of Kashmir.

Lahore is Pakistan's cultural capital but has also suffered from attacks by militant groups.

The number of attacks has risen since the landslide election of Prime Minister Nawaz Sharif in May elections.

Pakistan is home to a number of militant groups, including al-Qaeda, the Taliban and other sectarian groups.

The US State Department initially announced the wider embassy closures would be only for last Sunday, then extended the closures of some by a week and added Burundi, Rwanda and Mauritius to the closure list.

Yemen, one of the poorest Arab countries, is the base for al-Qaeda in the Arabian Peninsula (AQAP), one of the most active branches of the network founded by Osama bin Laden.

Militants have launched attacks from there against the West.

US sources have told Reuters that intercepted communication between al-Qaeda leader Ayman al-Zawahri and the Yemen-based wing was one part of the intelligence behind their alert last week.

Separately, nine people have been killed and 27 injured in the western city of Quetta.

Police said that gunmen fired on the vehicle of a politician driving past worshippers leaving a mosque on the Muslim holy day of Eid.

Quetta is the capital of eastern Baluchistan province, where several militant groups are active, including the Pakistani Taliban, who claimed responsibility for a suicide bomb attack that killed 30 people at a policeman's funeral yesterday.