PARIS, May 5 (Reuters) - French authorities are trying to make peace with the son of Pablo Picasso after he accused them of dishonouring his father by delaying the re-opening of the Picasso Museum in Paris.

The refurbished 17th century mansion housing the collection had been due to reopen in June, after a five-year, 52 million euro ($72 million) refurbishment. But the Culture Ministry said it would not now open until mid-September, missing the tourist season's summer peak.

"I am outraged and deeply concerned," Claude Picasso, the 66-year-old son of the painter seen as one of the 20th century's most influential artists, told Le Figaro newspaper.

"I get the impression that France couldn't give a damn about my father or me," he said in the interview, published on Friday just before the Culture Ministry confirmed in a statement its decision to wait until September.

Inaugurated in 1985, the Picasso Museum includes nearly 300 paintings including "Self-portrait" from his early Blue period through to "Matador" and others completed in the years before his 1973 death. It also includes some 250 sculptures, relief paintings and other works.

"What possible interest could the Culture Ministry have in hindering the re-opening and functioning of one of the country's most popular museums?" the ministry said.

"The Ministry appeals to everyone to put their own personal interests to one side and share the enthusiasm and calm required to complete this project," it added.

Addressing widespread incredulity in arts circles over previous official explanations that the delay was partly needed to recruit new guards, the statement also announced the creation of 40 new jobs "despite the tough budgetary climate".

The office of Prime Minister Manuel Valls could not immediately be reached to confirm a Le Monde report that Valls would receive Claude Picasso on Monday.

However the news daily noted that if anyone could calm the irate Picasso heir down, then Valls - who himself is the son of a Spanish painter who emigrated to France - could. ($1 = 0.7212 Euros)