MADRID--Hundreds of privacy experts from around the world met in Madrid Wednesday for a three-day conference which aims to arrive at a global standard for the protection of personal data.

US Homeland Security Secretary Janet Napolitano as well representatives from data protection agencies from 50 nations and top managers from key Internet firms like Google and Facebook are taking part in the event, billed as the world's largest forum dedicated to privacy.

Artemi Rallo Lombarte, the director of the Spanish Data Protection Agency, an independent control authority which is organizing the 31st International Conference of Data Protection and Privacy, said laws regulating privacy vary greatly around the world.

"These differences are far from being an obstacle, they should instead enrich our initiatives to promote the effective guarantee of rights through a global convention for the protection of privacy and personal data," he said in a opening address to the conference.

"This is one of the main goals of this international conference," he added.

Participants hope the international standards reached at the gathering will serve as the basis for a universal, binding legal instrument on data protection.

An extensive international consensus already exists to limit data processing to the purposes for which they were gathered and the need to ask users for their consent regarding international data transfers, organizers said.

Previous conferences on data protection and privacy have taken place in Strasbourg, Hong Kong, Sydney and Montreal.