Swiss justice authorities confirmed yesterday that they are investigating a World Cup TV rights contract signed off by Sepp Blatter that was sold to Jack Warner for a fraction of its true value.

Swiss attorney general Michael Lauber told a news conference in Zurich that Fifa had sent prosecutors its explanation for the contract sold to the Warner-controlled Caribbean Football Union for $600,000 (£389,000) — Warner’s company later sold them on for an £11 million profit.

Meanwhile, US attorney general Loretta Lynch announced more arrests and charges are likely as a result of the separate FBI investigations into Fifa corruption. Lynch, speaking at the same news conference, said new charges and arrests against “individuals and entities” were anticipated.

Lauber also revealed that assets including flats in the Swiss Alps and western Switzerland had been seized by his investigators, on suspicion of being used for money-laundering purposes, and that 121 different bank accounts had been brought to the attention of the investigating task force.

In May, the US Justice Department announced indictments against 18 people on football-related corruption charges — four have pleaded guilty to charges.

Lynch said: “Separate and apart from the pending indictments our investigation has expanded since May. The scope of our investigation is not limited and is following the evidence where it leads.

“We do anticipate pursuing additional changes against individuals and entities.”

Asked if Blatter was under investigation or if it might interfere with his travel plans — the Fifa president did not travel to the women’s World Cup in Canada in June following the arrests in May — Lynch added: “I’m not going to comment on individuals and I am not able to give you information about Mr Blatter’s travel plans.”

The Swiss and US investigations remain separate and Lauber’s disclosure that Swiss authorities are looking into the TV rights contract will set alarm bells ringing at Fifa.

In 2005, Blatter signed a contract selling the Caribbean rights for the South Africa 2010 World Cup and Brazil 2014 to the CFU for about 3 per cent of the sum that Warner sold them on for.

Mark Pieth, a Swiss professor of criminal law and Fifa’s former anti-corruption adviser, said Blatter should face a criminal investigation for alleged selling of such undervalued rights, saying there was “prima facie” evidence about the sale.

Pieth said: “Blatter has to defend himself against a form of embezzlement charges. They have prima facie evidence. That means they have to open an investigation.”