Pakistan police said Wednesday they had arrested nearly 1,000 protesters who marched on the capital demanding the release of jailed ex-prime minister Imran Khan, after crowds were evicted from the city centre in a sweeping security crackdown.

The crackdown brought a swift end to the protests that have gripped Islamabad, Pakistan’s capital, this week ever since thousands of people gathered in the city to demand the release of Imran Khan, the former prime minister. Mr. Khan has been in prison since last August on charges that his party claims are politically motivated.

Security forces clashed with protesters near Pakistan's parliament on Tuesday as hundreds of supporters of jailed former Prime Minister Imran Khan demanded his release in demonstrations the government said have killed four paramilitary troops.