PARIS, July 11 (Reuters) - France Telecom said the origin of a nationwide network outage over the weekend that left 26 million customers unable to make calls or send text messages was a software problem on Alcatel-Lucent equipment.
In testimony before France's National Assembly on Wednesday, Chief Executive Stephane Richard said that the software had undergone an update roughly 48 hours before the 10-hour outage.
"It seems that during this update, there was a problem, some sort of malfunction that was at the origin of the outage," he said.
Richard added that the software update was carried out by Alcatel-Lucent in conjunction with France Telecom staff.
The outage was the biggest disruption of communications seen in France since 2004 and has touched off government concern about the reliability of key national infrastructure.
The recently elected Socialist government has called for national audits of all the telecom operators' networks to ensure that they are up to snuff.
Alcatel-Lucent said on Wednesday that it was working with France Telecom to identify the "root causes" of the outage.
"At this stage we know this incident created an abnormally overload of the software provided by Alcatel-Lucent," said an Alcatel-Lucent spokesman in a statement to Reuters.
He added that Alcatel-Lucent had since provided a software patch to act as a monitoring tool while continuing to investigate the issue with France Telecom.
France Telecom will give all mobile customers a free day of calling in September to compensate them for the service disruption. Richard said that the incident will likely cost the company "several dozen million euros" and that a precise figure would be given on July 26 at the company's quarterly results. (Reporting by Leila Abboud and Gwenaelle Barzic; Editing by Gary Hill)