President Obama's spokesman evaded answering when asked for "specific" assurances about the National Security Agency monitoring Israeli Prime Minister Benjamin Netanyahu's telephone calls.

"I just don't have anything more specific about specific alleged [NSA operations]," White House press secretary Jay Carney said.

Obama had a telephone call last week with German Chancellor Angela Merkel in which he "assured the chancellor that the United States is not monitoring and will not monitor [her] communications," according to a White House readout of the conversation.

The Guardian (U.K.) reported that the NSA monitored communications of 35 world leaders. "We need to have trust in our allies and partners, and this must now be established once again," Merkel said last week.

"I repeat that spying among friends is not at all acceptable against anyone, and that goes for every citizen in Germany," she said.

Carney told reporters that "this is the kind of thing that merits review, and that's why the president initiated it."