The leaders of the US and Germany have admitted that the two governments have failed to reach a no-spying agreement.

US President Barack Obama met with German chancellor Angela Merkel on Friday, months after Edward Snowden, a former US surveillence agency contractor, revealed that Washington was spying on German officials, including Merkel.

Efforts to reach a deal preventing Washington from gathering intelligence on German soil have faltered.

Merkel said on Friday in a joint news conference with Obama at the White House that they had "a few difficulties yet to overcome".

Obama pledged to have "cyber-dialogue" on the issue, but said the US did not have a blanket "no spy" agreement with any country and that was not accurate to say Washington offered and withdrew a deal with Germany.

Spying on Merkel

A news report by German magazine Der Spiegel revealed in October 2013 that Merkel's mobile telephone had been listed by the National Surveillance Agency's Special Collection Service since 2002.

The magazine said it was not clear whether the SCS had recorded conversations or just connection data.

Germany's outrage over reports of the bugging of Merkel's phone by the US National Security Agency prompted it to summon the US ambassador in an unprecedented post-war diplomatic rift.

But the magazine also reported that President Obama told the German leader he would have stopped the surveillance had he known about it.

The issue has aggravated German citizens, prompting calls for Berlin to strike some type of agreement with Washington to limit US surveillance on German soil.