Police arrested Aleema Khan, the sister of Pakistan's jailed ex-prime minister Imran Khan at her house in Lahore, his party, the Pakistan Tehreek-e-Insaf (PTI), said on Sunday, ahead of a planned protest march by the party on 27 September.

A notification issued by Lahore's district administration said she has been arrested and sent to jail for 30 days.

"According to intelligence reports, her presence at any public place will pose a grave threat to public safety," the district administration said.

Imran Khan's party has organised a march to Islamabad next week demanding his release.

Pakistan's Interior Minister Mohsin Naqvi said on Saturday that the government would do everything it could to stop the protest march.

A close aide to Khan, Zulfi Bukhari, described the arrest of Khan's sister as "absolutely despicable".

"The fear of the 27th protest is clearly taking its toll," Bukhari added.