After days of muddled explanations for using government jet to attend Champions League final, Valls says he will pay back part of cost

The French prime minister, Manuel Valls, has expressed regret and said he will pay back part of the cost after taking a government jet to travel to Berlin to watch his favourite football team, Barcelona, play in the Champions League final.

The Barcelona-born Socialist was criticised by political opponents and some within his own ranks after it emerged that he had slipped away from his party conference this weekend to watch the match with two of his sons.

After five days of pressure, Valls addressed the issue on a visit to the Indian Ocean island of La Réunion. He said the Berlin trip, estimated to have cost around €15,000 (£11,000), was an official visit in the runup to France hosting the Euro 2016 tournament.

“Since this was an official trip, I used the means available to a prime minister. But I am of course sensitive to the reaction of the French people and I have to behave in a completely rigorous way. If the chance came up again, I wouldn’t do it again,” he said. “And to remove any doubt, I have decided to pay the costs for my two children, amounting to €2,500.”

He said flying his children with him on the official plane had led to no additional costs.

The scandal has been extremely damaging for Valls and is likely to dent his popularity ratings, which had been high. One poll found that 77% of French people were shocked by his use of the jet.

The row was worsened by three days of muddled explanations for the trip. Valls, who is normally considered one of the most astute communicators in the Socialist party, at first said it was an official trip, then added fuel to the fire by talking about his passion for football and insisting he was entitled to moments of relaxation given his hectic workload. It didn’t help when he attended the men’s final of the French Open tennis tournament the next day.

On the weekend of the Champions League final, Valls had been in Poitiers for the Socialist party congress, tasked with smoothing over cracks in the party and winning back MPs from the left who have opposed his economic policy. This delicate exercise had gone better than expected, with the prime minister winning applause for a rousing speech. But within 24 hours, the fractured party had returned to sniping.

The trip is being seen as Valls’s first serious political gaffe since he became prime minister last year. It was all the more damaging because the Socialist president, François Hollande, had promised that his term in office would be “irreproachable” in contrast to that of Nicolas Sarkozy. Valls himself has always taken a tough line against abuse of power by France’s political elite.

Despite Hollande’s promise of a squeaky clean republic, other ministers have been caught out. Jérôme Cahuzac, Hollande’s trusted tax tsar and budget minister, who vigorously led a crusade against tax-dodging millionaires, confessed to hiding €600,000 (£510,000) from the taxman in a secret foreign account for 20 years and lying about it. Then the French trade minister, Thomas Thévenoud, caused astonishment when he blamed his failure to pay rent or taxes on “administration phobia”.