Political parties in Pakistan have demanded a thorough investigation after a member of Pakistan Tehreek-i-Insaaf (PTI) party accused its founder and chairman Imran Khan of sexual harassment and quit the party.

Ayesha Gulalai alleged that Khan, a cricketer-turned-politician aspiring to become the next prime minister after Nawaz Sharif's recent ouster, has been sending her and other female party members "inappropriate and explicit text messages".

Gulalai made the disclosure on Tuesday (1 August) while announcing her exit from the party. She reportedly spoke just moments before the country was set to elect a new prime minister to replace Sharif, who was removed for his alleged involvement in the Panama Papers scandal.

Gulalai said she has been receiving the indecent messages from Khan since October 2013. She added that despite complaining about the ill-treatment of women party members, no action has been taken so far and hence, her decision to quit.

"No one with any honour will be able to stomach the sort of language used," she was quoted by Dawn as saying about the text messages.

"Maybe they think Pakistan is England. At this age, you [Imran] have not been able to reform your habits, maybe you do not have control over your behaviour."

Amid rumours that she was quitting PTI to join the opposition PML-N party, she told Dawn News: "Women workers are not respected in the PTI and a respectable woman worker cannot remain in the party." She also told reporters that she was not joining any other political party.

Meanwhile, PML-N leader Hanif Abbasi said on Wednesday (2 August) that Khan must respond to the "shameful" allegations.

"A grave allegation has been levelled against you (Khan) and you should have been ashamed, but you are not — because in the society that you come from, these matters are not considered shameful," Abbasi noted.

"If these allegations are not investigated, we will believe that justice has died. There should be an investigation, there should be a suo motu, so that the truth can be revealed."

Another opposition leader Khursheed Shah also made the same demand, saying: "The matter concerning Gulalai is regrettable. It should be investigated."

While Imran is yet to respond to the allegations, his party spokesman dismissed the charge, accusing Gulalai of "selling her soul to PMLN".