GENEVA - Heirs of a Qatari prince who died in 2000 are taking HSBC Suisse to court to obtain $2.6 billion they say he had on deposit with the bank, the Swiss weekly Le Matin Dimanche reported Sunday. They allege that the Geneva-based bank refused them access to the account of Khalifa bin Ali bin Abdullah al-Thani, the late billionaire brother of Qatar’s last emir. The Geneva public prosecutor confirmed to the paper that his sons are suing for the restitution of the $2.6 billion. The paper quoted a source as saying that the dispute went back some 30 years, while the bank declined to comment.