ISLAMABAD - Twitter users in Pakistan faced internet censorship with Pakistan's telecommunications regulators blocking access to the social networking site for about eight hours Sunday before the prime minister stepped in to restore access.

The sudden blocking of the site followed Twitter's failure to remove content the government found objectionable to Muslims.

The Internet censorship caught many of the officials, lawmakers and politicians who regularly use Twitter by surprise, reported Washington Post.

The government did not specify which users or messages had prompted the ban or why it was restored within a day.

Interior Minister Rehman Malik insisted that Twitter had not been blocked, only to realize that he had been misinformed.

A regular Twitter user, Malik told the Post on Sunday evening that Prime Minister Yousuf Raza Gilani ordered Information Technology Ministry to restore access to the site.

The offensive tweets apparently had reference to a competition on Facebook that Muslims worldwide have denounced for encouraging blasphemy.

Two years ago when the competition was launched, the Lahore High Court had ordered that the Facebook page hosting it should be blocked. An estimated 1,000 other websites were also blocked for carrying blasphemous content.

In negotiations with Pakistani officials, Facebook agreed to continue to prevent the controversial page from being accessed in Pakistan which led to the ban being lifted after nearly two weeks. But Twitter would not cooperate, said PTA chairman M Yaseen.

The refusal of Twitter to cooperate led to the Ministry of Information and Technology ordering the telecom providers to block Twitter access in the country.

It was not immediately clear who in the government directed that the Twitter site be blocked on Sunday afternoon. Yaseen only stated, "It is a high-level decision."

The Internet Service Providers Association of Pakistan said its members had been asked to block Twitter indefinitely, but no reason was provided by the government.

The ban did not deter Twitter users, with some of them downloading software to circumvent the ban, while others continued to tweet using smartphones.

"As a citizen of Pakistan and as a former journalist I condemn the blocking of Twitter. Freedom of speech is an inviolable right," tweeted Farahnaz Ispahani, a member of Parliament and media advisor to President Asif Ali Zardari.

Interior Minister Rehman Malik, an active Twitter user, said on the website Sunday night that he had intervened and asked the prime minister to get the ban lifted.