Former president Pervez Musharraf would face arrest if he returned to Pakistan after police registered a case against him on Tuesday over his detention of judges during a political crisis in 2007.

The military dictator, who came to power in a coup in 1999, left Pakistan more than two months ago, having been forced to quit as president in August last year in order to avoid impeachment by a hostile parliament.

"He could either be arrested on his return or through Interpol," Hakam Khan, head of a police station in Islamabad where the case was lodged, told Reuters.

If convicted Musharraf could be jailed for three years, Khan said.

This is the first time that such a case has been brought against a former military ruler.

"He detained judges and ousted them illegally so he has to be tried for his illegal and unconstitutional actions," Mohammad Aslam Ghuman, the lawyers who filed the case against Musharraf, told Reuters.

Earlier this month the Supreme Court ruled that Musharraf had violated the constitution by imposing emergency rule and purging the judiciary in November 2007 in a desperate move to hold onto the presidency.

The court left it up to parliament whether Musharraf, once a vaunted ally of the United States, should be tried for treason for his actions.

With the knives out for him at home the old general has spent most of his time since late May in London and he is believed to be looking to settle in Europe.

Outrage over the use of emergency powers and detention of opposition figures, including the judges, contributed to the defeat of Musharraf's allies in an election in 2008. - Reuters