There was no official word on the development but users from different parts of Pakistan, especially Islamabad and the nearby garrison city of Rawalpindi, reported that they were unable to access the site on their computers and mobile phones.
The move came hours after Interior Minister Malik himself tweeted early this morning that the government had no plans to impose restrictions on Twitter and Facebook.
"Dear all, I assure (you) that Twitter and (Facebook) will continue in our country and it will not be blocked. (Please) do not believe in rumours," he said in a tweet.
In another tweet, Malik dismissed a question from a New York Times reporter about reports that the government intended to restrict access to Twitter.
"Why (should) I even think of doing so?" Malik asked.
Yesterday, TV news channels had quoted Information Technology Minister Raja Parvez Ashraf as saying that the government could restrict access to Twitter and Facebook as the sites were being used to circulate blasphemous caricatures.
More From This Section
In the past, the Lahore High Court was ridiculed by internet users and commentators after it briefly banned Facebook over blasphemous caricatures of Prophet Mohammed.
Civil society and rights groups and activists have made use of Twitter in several recent campaigns.
The government recently dropped plans to acquire sophisticated equipment to block and monitor websites after a campaign on Twitter and several other websites.