Five estranged Pakistan Tehreek-i-Insaf (PTI) lawmakers on Monday sent defamation notices to party chief Imran Khan for levelling allegation that they sold their votes during the Senate elections held in March.

Imran Khan, in a press conference in April, had revealed the names of 20 MPAs from Khyber Pakhtunkhwa who were allegedly involved in horse-trading during the Senate elections.

Qurban Ali Khan, Yaseen Khalil, Abdul Haq Khan, Zahid Durrani and Ubaidullah Mayar — among the 20 named by the PTI chief — sent defamation notices to the PTI chief on Monday, demanding an apology within 14 days and payment of damages amounting to Rs1 billion or face legal proceedings.

Terming the allegations against him as totally false and defamatory, Qurban Ali, in his legal notice, also alleged that he was defamed and removed from the post of adviser to Chief Minister Pervaiz Khattak after he refused to illegally appoint people according to Khattak's wishes.

The PTI chief had held the press conference last month after his party lost the Senate seats to the PPP it was expected to win.

The lawmakers mentioned by Imran had denied the allegations with some threatening to disclose "secrets" of party leadership, including Khattak and Imran Khan himself.

Mayar and Durrani have since joined the PPP.