Five years after it closed for a two-year renovation, Paris's Picasso museum – which houses one of the world's most extensive collections of the Spanish master's work – will finally reopen its doors in September, the culture ministry announced Sunday. It had intially been due to open in June.

The delay has caused controversy, with the painter's son Claude Picasso on Friday accusing the French government of indifference and saying he was "scandalised and very worried" about the future of the museum.

"This opening was supposed to be a great party. They are turning it into a fiasco," he told Le Figaro.

"The truth is that there is positively no desire to open the museum. I am being taken for a ride. I get the impression that France is making a mockery of my father and of me," he said.

Claude Picasso was called to the French prime minister's office on Monday where he was presumably offered an apology and an explanation for the postponement.

He asked the government to do its best to ensure that the establishment reopens in June, as announced earlier this year by the gallery's president Anne Baldassari.

Jean-Francois Bodin, the architect in charge of the renovation, had said on Saturday that the museum could still be reopened at the end of June as scheduled.

Culture Minister Aurelie Filipetti said in a statement that her ministry had decided to reopen the museum to the public in mid-September because the main renovations were only completed on April 30 and time was needed to finish the rest.

She made an appeal "for everyone to overcome personal interests and show enthusiasm and calm to allow the project to be completed".

The final bill for the refurbishment of the 17th-century baroque mansion in Paris's historic Marais quarter now stands at €52 million ($71 million), €22 million higher the original budget due to changes in the scope of the work.

The museum's exhibition space will be more than doubled to 40,000 square feet (3,800 square metres) after the renovation.

Although the musuem has around 5,000 paintings, drawings, sculptures, ceramics, photographs and documents, previously only a fraction could be displayed at any one time due to limited space.

There will also be a corresponding rise in the number of visitors that can be admitted at once from 380 to 650, and annual admission figures are expected to jump from 450,000 to 850,000