The coalition partners appear to be on a collision course over government plans to give the security services new access to internet data after the Liberal Democrat president said his party was prepared to "kill" any moves towards universal surveillance.

Tim Farron issued his warning shortly after Theresa May, the home secretary, said she hoped to introduce legislative changes after the Queen's speech next month because of the importance of moving quickly.

In a sign of a possible battle when draft clauses of a new parliamentary bill containing the plans are published, Farron said the Lib Dems would resist any threat to a free and liberal society.

"We are prepared to be kill them – I mean to be absolutely clear about that – if it comes down to it," Farron told James Landale in an interview on the Andrew Marr Show on BBC1. "If we think this is a threat to a free and liberal society, then there'll be no question of unpicking them or compromising. This just simply must not happen."

Farron was asked about remarks by the home secretary in the Sunday Telegraph in which she said a bill would be introduced soon. May said: "Obviously the longer you leave it, the quicker technology can move on. I would hope that we will be able to do this in a bill. I would expect us to be able to do this in a bill in the next session, but in a way that enables people to have a sight of the clauses."

Farron said: "It's interesting to hear her say that. I would be very surprised if we ended up in a situation where any bill that looked anything like the press reports that were talked about earlier this week got anywhere near the House of Commons. If it did, then Liberal Democrats would not support it."

The apparently contradictory positions of Farron and May follow a row last week between Nick Clegg's office and the Home Office after the Sunday Times reported that the government was reviving a Labour plan, dropped in 2006, to "scrutinise 'on demand' every phone call, text message and email sent and website accessed in real time".

The deputy prime minister's office believes the Home Office inflamed matters by failing to explain properly that the government was simply planning to expand existing powers, which cover more traditional forms of communication, to new technology. The changes would mean that the Government Communications Headquarters (GCHQ) would be given real-time access to Skype, instant message and email data.

The government stressed that the proposals covered data on where a call is made from, when and by whom. The authorities would still need a warrant to access the contents of such communication.

Clegg says he supports the changes because many criminals and terrorist suspects are exploiting the loophole in the law to communicate in a way that cannot be monitored. But he wants civil liberties groups to be given the chance to challenge the proposed changes when the draft clauses are published after the Queen's speech. The deputy prime minister told the Guardian he deferred to Shami Chakrabarti, the director of Liberty, "when it comes to being a guardian on the high principle of liberty and liberalism".

Farron made clear that he supported Clegg's position, indicating that his language about a threat to "kill" the plans applied to the portrayal of the measures before the Lib Dems intervened.

"I'm in no mood whatsoever to apologise for or to amend or unpick authoritarian legislation. It strikes me that a Liberal Democrat or a government that includes Liberal Democrats should ensure that Britain ends up a more liberal place, not less. Like many of us who are Liberals, [I was] very horrified by the original press reports about what the surveillance measures might lead to. There must be absolutely no question of universal internet surveillance across this country.

"My conversations with the deputy prime minister and others reveal that there's been significant movement this week. I suspect a lot of the reports are exaggerated, but if they weren't then no such bill should get anywhere near the House of Commons."