Hong Kong police searched the student union office at Polytechnic University on Friday in connection with clashes between radical protesters and officers that broke out at the campus last year. But several students blocked the entrance in an attempt to stop police from entering the office in the university’s Shaw Amenities Building in Hung Hom shortly before 12.30pm. Students also demanded officers show their warrant cards and the court warrant police obtained to allow the search. One union representative said they had to seek legal advice, but police said the representative had been told about the search two weeks ago. After a 30-minute stand-off, officers entered the office to gather evidence at about 1pm. The search ended at about 2.30pm when officers left with two plastic boxes of items including a computer. No arrests were made. The PolyU campus was the site of one of the biggest clashes between radicals and police during last year’s anti-government protests . A siege at the university began on November 17 after pitched battles turned the campus entrance into a war zone. Officers sealed the exits and asked all those inside to leave. During the conflict, radicals threw petrol bombs, police fired tear gas, an armoured car was set alight, and one officer was also shot in the leg with an arrow. From war zone to ‘prison’: voices from Polytechnic University siege Police declared the daytime violence on November 17 a riot before laying siege to the campus, which was occupied for 13 days by radicals. After the end of the siege, police seized about 4,000 petrol bombs, 1,339 pieces of explosives, and 601 bottles of corrosive liquid, along with 573 other items classified as weapons. These included hammers, air guns, 28 bows and about 200 arrows, and 12 giant catapults used to fire bricks.