(CNN) -- Allegations that the United States is spying on its European allies topped the agenda for European Union ambassadors who met Thursday in Brussels, Belgium, as the fallout from claims made by U.S. leaker Edward Snowden widened.
The meeting of the ambassadors to the European Union came ahead of talks due to begin Monday on a huge American-EU free trade deal.
They were expected to discuss the spying allegations as well as revelations about PRISM, the mass U.S. surveillance program, and a proposal to establish an EU-American working group to improve cooperation, EU spokesman Michael Mann said ahead of the meeting.
Allegations that the United States has been conducting surveillance on its European allies have prompted wide concern among European nations.
The issue dominated a conversation Wednesday between President Barack Obama and German Chancellor Angela Merkel.
"The president assured the chancellor that the United States takes seriously the concerns of our European allies and partners," a White House statement on the phone call said.
Joint EU-American discussions are to be held on the collection and oversight of intelligence, and questions of privacy and data protection, starting as soon as Monday, it said.
The European Parliament voted Thursday in favor of launching an in-depth inquiry into the U.S. surveillance programs, including the alleged bugging of EU premises.
In the resolution, approved 483-98 with 65 abstentions, European lawmakers expressed concern over PRISM and other surveillance programs, strongly condemned spying on EU representations and called on U.S. authorities to provide full information on the allegations without further delay, according to a statement from the European Parliament.
The inquiry by the body's Civil Liberties Committee will gather evidence from U.S. and EU sources and present its results by the end of this year, it said.
The lawmakers also urged European authorities to "consider recourse to all levers at their disposal in negotiations" with the United States, including suspending the current deals on air passenger and bank data.
EU data protection standards should not be undermined as a result of the EU-American trade deal, the resolution warned.
Lawmakers also voiced "grave concern" over allegations that similar surveillance programs are run by several of the 28 EU member states, such as the United Kingdom, Sweden, the Netherlands, Germany and Poland, the statement said.
France calls for delay
French government spokeswoman Najat Vallaud-Belkacem said Wednesday that France believes it would be wise to delay American-EU trade talks for two weeks in light of the allegations.
She was echoing remarks made by French President Francois Hollande this week after the allegations first appeared in German and British media.
But the European Commission, which will lead the negotiations for the EU, said the talks would go ahead as planned despite worries about potential snooping.
"Whilst the beginning of EU-U.S. trade negotiation should not be affected, the EU side will make it clear that for such a comprehensive and ambitious negotiation to succeed, there needs to be confidence, transparency and clarity among the negotiating partners," it said in a statement.
German Economy Minister Philipp Roesler said the reports of spying would influence the planned talks, according to his spokesman, Adrian Toschev.
But the spokesman declined to back the French call for a delay to the negotiations.
Sweep for listening devices
German news magazine Der Spiegel reported Sunday that classified leaks from Snowden, a former National Security Agency contractor, detailed how the agency bugged EU offices in Washington and New York as well as conducting an "electronic eavesdropping operation" that tapped into an EU building in Brussels.
Obama said Tuesday he needed more information on the specific programs cited in the report but made clear such spying was commonplace.
"I guarantee you that in European capitals, there are people who are interested in, if not what I had for breakfast, at least what my talking points might be should I end up meeting with their leaders," Obama said. "That is how intelligence services operate."
The European Commission will sweep its offices for electronic listening devices and other security breaches, a spokeswoman said Monday.
A comprehensive EU-American trade deal would be the biggest of its kind and could add $160 billion to annual European income, $125 billion to U.S. income and $133 billion to other economies.
Together, the United States and EU account for about half of global economic output and trade some $1 trillion in goods and services each year, supporting about 13 million jobs on both sides of the Atlantic.
CNN's Antonia Mortensen and Alanna Petroff contributed to this report