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.

Asked about the matter, government spokesman Stephane Le Foll said Sarkozy was "subject to justice like everyone else."

"Justice authorities are investigating and have to go all the way," he told i

Under French law, influence-peddling can be punished by up to 5 years in prison and a fine of 500,000 euros ($682,000). Sarkozy lost presidential immunity from legal prosecution a month after he left office in June 2012.