The BBC's Mike Baker: "Rallies are going on all over the country"

The Association of University Teachers (AUT) has set up picket lines at universities, as lecturers and other staff begin a campaign of strikes that threatens to bring disruption to the summer term.

Members voted for strike action after the union rejected a 3.5% pay rise, an offer which the union said made no progress towards closing the gap between salaries in higher education and other public sector professions.

The union says it wants a 10% increase this year as the first stage towards a major upgrading of academic salaries, which have slipped more than 35% behind comparable professions in the past 20 years.

The AUT's General Secretary, David Triesman said: "This major disruption to universities must persuade the employers to improve their 3.5% offer if we are to avoid a programme of action later in the summer."

Lecturers say they will escalate action throughout the summer term

As well as announcing one-day strikes, the union plans to step up pressure on the government with a threat to disrupt this year's admissions process and the summer exams.

The union has said that its members will stage short-notice disruptions which fall short of strike action, including stopping administrative work, unplugging phones and refusing to answer e-mails.

The dispute is so far only affecting "old" universities, as the "new" universities - former polytechnics which obtained university status in 1992 - are on a different pay bargaining cycle.

The Conservatives' higher education spokesman, Damian Green, said he did not support strike action but was sympathetic to university staff who felt "let down" by the government.

"For all the government's talk about extra money going to universities, those who work in them have seen little evidence of any improvement either in pay or in the services provided to students," said Mr Green.

A spokesman for the Department for Education and Employment said pay was an issue for university employers.

"But we regret any action taken by lecturers which would damage the interests of employers," he added.

The National Association of Teachers in Further and Higher Education (Natfhe) represents lecturers in most of the new universities.

It is also seeking a 10% pay RISE this year, and has warned that a rise similar to that offered to the AUT is likely to lead to industrial action by its members.

An emergency resolution laying the ground for industrial action is expected to be tabled at the union's ANNUAL conference in Southport this weekend, before the opening of talks with employers next week.