At the start of an inquiry into American government communications surveillance programs Thursday, European parliamentarians (MEPs) were told to expect further revelations of mass spying by the U.S. National Security Agency (NSA).

Prominent hacker and Internet activist Jacob Appelbaum told the European Parliament’s civil liberties committee (LIBE) that more information about government spying, this time involving private home Wi-Fi, is bound to come to the attention of the public.

LIBE heard from people connected with NSA leaker Edward Snowdon, including Alan Rusbridger, editor of The Guardian and Jacques Follorou, journalist for French newspaper Le Monde. The Guardian published initial revelations of NSA spying based on information from Snowden in June.

Appelbaum, meanwhile, said during Thursday’s hearing that other leaks about NSA programs will reveal that the agency is hacking into personal Wi-Fi networks. He said it stands to reason that when surveillance by other means cannot be done, home Wi-Fi networks will be hacked.

“Where you have communications satellites, you’ll have other satellites behind them,” he continued. “The NSA collects everything. We have a planetary surveillance system that is not accountable to the people.”

Rusbridger, who oversaw the publishing of the Snowdon articles, noted that great pains had been taking to protect the material involved in reporting the government surveillance stories. “Whether mass collection of data is compatible with a free society comes down to effective oversight,” he said, adding that the technicians who build surveillance tools will always be ahead of laws that address privacy issues.

The committee is investigating the extent of data surveillance by U.S. authorities as well as any monitoring carried out by E.U. countries in the wake of the reports about NSA spying, including a U.S. program known as PRISM.

The Echelon system

At the hearing Thursday, MEPs also reviewed the Parliament’s 2001 inquiry into the Echelon system for global communications interception, which involved the U.S., the U.K., Canada, Australia, and New Zealand. However, Applebaum said that although the inquiry into Echelon was important, as it was the first time politicians were taking data interception seriously, “Echelon was child’s play compared to PRISM-like programs.”

The committee is supposed to present its findings by the end of the year and is expected to gather evidence about the alleged spying, its scope and impact as well as make proposals for redress in the event of confirmed violations of data-protection laws.

European Digital Rights (EDRi) and the Fundamental Rights European Experts Group (FREE) called on the committee to bring the activities of national security agencies in Europe and the U.S. “under the rule of law” and presented an analysis of how they think this can be done.

“They have been outside the scope of effective democratic oversight and outside clear legal frameworks for too long,” said EDRi spokesman Joe McNamee.