Prominent artists have spoken out against an “arbitrary reshaping” of Belgium’s museum landscape, as the Flanders region seeks to cut public spending by dismantling the country’s oldest contemporary art museum and transplanting its entire collection to another city.

At a press conference in Antwerp on Tuesday, the directors of the city’s Museum of Contemporary Art (M HKA), which was founded in 1985, decried what they called the “flagrant illegalities” of the museum sector shake-up, which is due to be debated in Belgium’s parliament on Friday.

In October, the culture minister of the Flanders region cancelled the planned construction of a new, purpose-built €80m high-rise building to house the museum, and announced plans to move its collection of 8,000 artworks to Ghent’s Municipal Museum of Contemporary Art (Smak), a surprise move that will in effect strip the Antwerp institution of its museum status.

“Antwerp is Flanders’ biggest city, with a legacy as a home of the avant garde in Belgium,” said Luc Tuymans, an Antwerp-based painter widely seen as Belgium’s most influential living artist.

“To degrade a museum to an arts centre is simply insane. You cannot simply take a collection of artworks and transplant it into another ecosystem, because such an ecosystem does not exist.”

The Antwerp museum’s collection also includes works by international artists such as Kerry James Marshall, Anish Kapoor and Marina Abramović.

British artist Kapoor has protested against plans to move his works to Ghent, telling the culture ministry in an email seen by the Guardian: “I cannot accept that they might be removed from M HKA or otherwise put at risk as part of any institutional reorganisation.”

Belgium faces a budget deficit of 5.4% of GDP, one of the largest in the eurozone. The arts sector in particular is facing dramatic cuts, with austerity measures also suggesting an uncertain future for Brussels’ new Kanal museum, originally designated to become one of the largest new arts complexes in Europe when it is scheduled to open at the end of this year.

Under the proposals of Flanders’ socialist culture minister, Caroline Gennez, the museum sector would be streamlined so that art collections in the region are concentrated at three beacon museums for historical, modern and contemporary art.

Flanders has a plethora of contemporary art museums: in addition to M HKA in Antwerp and Smak in Ghent, there is Musea Brugge in Bruges and Museum M in Leuven.

Whether the proposed shake-up would actually lower costs has been questioned by Belgium’s financial inspectorate, however. In a memorandum sent to Gennez in October, it gave an unfavourable opinion on the proposals, suggesting their impact on the budget would be “fragmentary”.

While transplanting the museum’s permanent collection could reduce operating costs from around €8m to €5m, it is understood that in future the Antwerp institution would have to spend money to borrow works or buy in exhibitions to attract visitors.

Ghent’s Smak, located about an hour’s train ride from the Antwerp museum, is also thought to currently not have enough space to adequately store M HKA’s collection, and would need investment to expand its storage capacity.