"The story is simple. Middlesbrough are going to pay the five million euros asked for by Paris Saint-Germain," he said.
"Normally, a transfer is paid in two instalments - so Middlesbrough pay 2.5 million euros now and the other half later.
"But Paris need liquid assets. Paris want the five million euros immediately.
"So I am irritated. It has taken too long. I am trying to meet up with the board but they aren't daring to make a decision.
"Quite simply, they are all incompetent."
He also launched a verbal volley at new PSG president Charles Villeneuve, adding: "When I think that he has even refused to meet the Middlesbrough chairman, who came over especially to sort this problem out.
"Mr Villeneuve prefers to send someone else to talk. I am going mad. This club is doing my head in. I can't stay."
Digard returned to training with PSG on Monday but should soon be on his way to Middlesbrough.
He came to the capital from Le Havre with a big reputation, but injury affected his campaign and he barely featured during the second half of the season.
He admits he is fortunate Middlesbrough have shown an interest.
"I am pretty lucky because I have only played for three months (last season), and only one month in my real position," he told L'Equipe.