Another world leader is urging tougher action against Iran and its nuclear program.

After talks Monday with Lebanese Prime Minister Saad Hariri, German Chancellor Angela Merkel said Iran has failed to agree to "constructive offers" put forth by nations negotiating with Tehran.

"We are about to enter the stage where sanctions should be taken against Iran," she said.

The U.S., Britain and France are also pushing for more sanctions, while China and Russia are calling for diplomatic negotiations.

Iran has insisted its nuclear program is harmless.