ISLAMABAD (AP) — The key opposition party led by recently ousted Prime Minister Imran Khan accused police of detaining dozens of its supporters Monday in an attempt to foil a planned protest seeking to force Pakistan's government into calling early elections.

Fawad Chaudhry, a spokesman for Khan's Tehreek-e-Insaf party, said the police operation began just after midnight and officers were still raiding the houses of supporters late in the day.

Khan took to Twitter, condemning the arrests of his supporters.

No government official was immediately available for comment.

The development came two days after Khan urged his supporters to gather in Islamabad on Wednesday for a demonstration that he said would continuuntil the government announced a date for snap elections.

Khan, who served as prime minister for over three and half years, was ousted by a no-confidence vote in parliament in April. He was replaced as prime minister by Shahbaz Sharif.

Khan contends his removal was the result of a U.S.-organized plot. Washington has denied the claim, and Sharif calls it a pack of lies.