Council workers stormed the Civic Centre in Southampton moments before the councillors finalised £25m budget cuts.
A protest was held by Southampton City Council staff over job cuts, just minutes before the budget announcement.
Security guards tried to stop at least a dozen protesters from entering the building. Once inside, some banged on the door of the council chamber.
The council has announced further cuts as it tries to save £25m in 2011-12.
All workers at the Conservative-run authority earning more than £17,500, which is 65% of staff, will now have their pay cut.
The council, which employs 6,629 staff, will now cut 290 posts.
Members of the Unison and Unite trade unions held the rally at the front of the Civic Centre at lunchtime.
'Not a choice'
Steve Brazier, regional manager for Unison's south east branch, said: "The view is the council is blackmailing staff into accepting a pay cut, or accept job losses, which is not fair.
"This is not a choice that people voted for. These proposals prove it was a lie when the government claimed front-line services would not be affected by their cuts.
"Jobs will go and people who provide jobs will be directly affected."
Staff earning £17,500 to £22,000 will have their pay cut by 2%, those in the £22,000 to £35,000 bracket will have pay cut by 4.5%, salaries of £35,000 to £65,000 will be slashed by 5% and those those earning more than £65,000 face a 5.5% cut.
Leader of the council, Councillor Royston Smith, said the authority would strip out bureaucracy and increase spending on roads, protecting children, strengthening the economy and creating new jobs.
Mr Smith said the budget would protect a further 400 jobs from being lost.