The reopening of Paris’ Musée Picasso – scheduled for June – has been delayed again. The museum, home to one of the world’s most extensive collections of Pablo Picasso’s artwork, has been closed for more than four years for renovation and expansion.

A new, vague opening date of by year-end has been set by France’s Culture Ministry for the government-run museum.

The US$71m (€51.4m, £42.4m) renovation and expansion project is the work of French architect Jean-Francois Bodin and is largely complete, aside from a few unspecified “technical details”. Local media cited security concerns by the ministry as the reason for the delay, but these reports have not been confirmed.

The museum’s exhibit space has been nearly doubled, with offices and workshops moved off-site and a previously unused space on the top floor of the building coming into play. An education space, an auditorium and a terrace cafe have also been added.

As a result, Musée Picasso will now be able to display a greater number of the 5,000 works and artefacts it currently holds. Much of the collection was left to the French state after Picasso died in 1973.

With the revamped museum also hosting rotating exhibits and cultural events, visitor numbers are expected to grow from 450,000 to 850,000 per year.