Pakistani mobile phone operators on Monday deferred the implementation of an order to block nearly 1,700 offensive and obscene words from SMS messages, saying they were holding discussions with the telecom regulator on the issue.

The Pakistan Telecommunication Authority recently issued two lists of offensive English and Urdu words and terms – containing 1,106 and 586 items respectively – that it wanted mobile operators to block.

The move was greeted with ridicule and derision by millions of mobile and internet users.

"We are in discussions with the regulator to evaluate this proposal. Once we reach a mutual agreement, we will take appropriate action," said Omar Manzur, spokesman for Mobilink, Pakistan’s leading telecom operator.

Asked if it would be feasible to filter so many words and phrases from the millions of text messages sent every day, Manzur told PTI: "That is part of the discussions. We are reviewing if that will be technically possible."

Officials of other mobile phone firms, who did not want to be named, said they had concerns about the PTA''s proposal, which has been criticised by rights activists.

The officials said the measure could severely disrupt SMS communications. Rights group Bytes for All said it would challenge the PTA's directive in court, describing it as a "ruthless wave of moral policing" that violated rights to free speech and privacy.

"We are talking to a few lawyers to take this matter to court. We will file a petition if this directive is not withdraw," Shahzad Ahmad, country coordinator for Bytes for All Pakistan told PTI.

Ahmad contended that PTA had not done any study before issuing the directive and the measure would cripple mobile phone networks.