Radical protesters unleashed chaos in and around the university on November 17, triggering violent exchanges of petrol bombs and tear gas with police. The force declared the unrest a riot, before surrounding the site. Thousands of petrol bombs and other weapons were recovered from the grounds after the siege came to an end on November 29.

The latest progress was touched on in a letter jointly issued by president Professor Teng Jin-guang and five vice-presidents, to staff and students on Monday.

The management also thanked those who had helped in the restoration work, saying: “During the peak period, about 400 people were engaged in related work daily, including a large number of alumni, from a professional construction company run by [an alumnus], providing voluntary services.”

Professor Teng earlier faced criticism and accusations that he failed to control his institution.

In Monday’s letter, management said it “once again, strongly condemns the acts of vandalism and violence on the campus”.

But it defended its handling of the trouble, saying its primary goal was to ensure the personal safety of all people involved, “to ensure a peaceful and humane resolution of the crisis and to avoid severe confrontations that could cause casualties”.

It also sought to ease staff’s concerns about working on the campus.

“We have carried out preliminary safety assessments of the buildings on campus, including the testing of indoor air quality, filter replacement of air-conditioning systems and assessment of building structural safety, as well as the decontamination of individual buildings.

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“After internal assessments and testing, some buildings and laboratories were deemed to be safe and were reopened so that colleagues and research students who wished to work there could enter.

“About half of the campus is expected to reopen by the end of December, and the rest ... by mid-January next year, so that semester 2 will commence as scheduled on January 13, 2020.”

The letter did not mention the cost of the repairs.

Professor Teng had earlier said the university would hire professionals to provide an estimate of the costs and he expected a major part of the money to come from the government.

Officials have said universities which struggle to pay the huge repair bills could seek help from the Education Bureau or consider applying for funding at the Legislative Council.

Last month the government pulled about HK$2 billion worth of separate funding proposals under consideration at the Legislative Council, for use on medical and library facilities at three universities, including Polytechnic University, after some pro-establishment lawmakers expressed dismay that varsity management had, as they saw it, failed to control their institutions, allowing them to become battlefields in the protests.