(CNN) A court in Pakistan has ordered the arrest of former Prime Minister Nawaz Sharif's brother, Shahbaz, ahead of the two men's expected return next week.
The brothers, who were exiled following a 1999 coup which ousted Nawaz Sharif, have vowed to return home on Monday.
Shahbaz Sharif denies ordering the extra-judicial killings of five people when he was in power in the 1990s.
Observers say Nawaz Sharif's return poses the most serious threat yet to Gen Pervez Musharraf who ousted him.
If the government uses illegal tactics and blocks them... that will bring people onto the streets
Ahsan Iqbal,
PML-N spokesman
Nawaz Sharif could also be arrested on his return. He and his brother both face corruption charges, which they deny.
Meanwhile, police raids on houses of Sharif supporters have continued in Punjab province. Hundreds have now been detained.
'Politically motivated'
The judge in the eastern city of Lahore ordered police to arrest Shahbaz Sharif "at whichever airport he lands", said a lawyer for the Sharifs.