About 60 rowdy protesters, who had been yelling, chanting and making noise — including with a trumpet — from outside the building during Mr Brown’s 15-minute announcement, moved to block his exit from the New Hospital Project Management Office in Castle St afterwards.
The protesters carried "They save, we pay" hospital campaign placards with messages such as "Health cuts hurt" and "Simion [sic] you make me sick".
Officers formed a line either side of the door to push protesters back so the minister’s car could get out.
Earlier, protesters gathered ahead of the announcement to voice their demand that the government build "the hospital that was promised to us", one of them, Sam Bosshard, said.
Third-year medical student Patrick Gibbons said he just wanted them to get on with the project.
"I’m not optimistic we will get what we were promised, but we need it."