French rugby federation (FFR) president Bernard Laporte broke down in tears on Thursday and vowed to return with renewed strength after he was released from police custody as part of an investigation into suspicions he favoured Top 14 club Montpellier.

Laporte, who is also vice-chairperson of World Rugby, is suspected of putting pressure on the appeals committee of the French league to reduce a disciplinary punishment against Montpellier in 2017.

The side's billionaire owner Mohed Altrad and the chief organiser of the 2023 Rugby World Cup in France, Claude Atcher, as well as two senior FFR officials, were also freed from detention.

Laporte wrote on Facebook.

he added.

At a news conference later on Thursday, Laporte was in tears and had to stop for a few moments in order to compose himself.

"I slept very well last night. I will leave with strength, enthusiasm and conviction to help the amateur clubs who need it. We will win on 3 October. I will put things right," added the 56-year-old who is standing for re-election as FFR president with the result expected on 3 October.

"It is not easy to be in custody. The same day in an article, he (Florian Grill, his rival in the election) declared that I set the federation on fire. That is to kick a player when he's down.

"If they are his rugby values, he must leave our sport."

Laporte hinted he has become a victim of a dirty tricks campaign in the run-up to the vote next month.

"This was just in the media. With less than 10 days to go to our deadline, I legitimately ask myself. Who could profit from this storm?" Laporte said.

"Now knowing the position of this investigation, I am more serene than ever," he added.

Laporte, who has also served as French sports minister, has always denied intervening in favour of Altrad's side but admits he had a telephone conversation with the head of the appeals committee, Jean-Daniel Simonet, before the decision was changed.

Three months before the alleged events, the Altrad group, specialised in construction materials, was named France's shirt sponsor and threw its financial muscle behind the successful bid to host the World Cup in three years' time.