Former French President Nicolas Sarkozy was held for questioning on Tuesday over suspicions he used his influence to secure leaked details of an inquiry into alleged irregularities in his 2007 election campaign.
It was the first time a former French head of state has been held in police custody and is the latest blow to Sarkozy's hopes of a come-back after his 2012 election defeat by Socialist rival Francois Hollande. The conservative politician denies all wrongdoing in a string of investigations involving him.
Sarkozy arrived early on Tuesday to be quizzed by investigators at their offices in Nanterre, west of Paris, after his lawyer was also held for questioning on Monday.
Seven French tourists have been kidnapped by gunmen in Cameroon, near the border with Nigeria, French President Francois Hollande has said.
He says they belong to the same family and were seized by a "known terrorist group based in Nigeria".
Mr Hollande added that the seven - including four children - were probably taken to northern Nigeria. Cameroon's government later confirmed this.
France urged all its nationals in the area to leave as quickly as possible.
The French foreign ministry said on its website citizens were "officially advised not to go to the far north of Cameroon (the shores of Lake Chad in the South Maroua), and the border with Nigeria, until further notice".
Mr Hollande said the Nigerian Islamist group Boko Haram may have been behind the kidnapping.
