Kerry mourns death of Iranian president's mother

U.S. Secretary of State John Kerry on Friday mourned the death of Iranian President Hassan Rouhani's mother, just as the world powers and the Islamic republic are negotiating hard over a nuclear framework agreement.

"We extend our deepest condolences to the president of the Islamic Republic of Iran, Dr. Hassan Rouhani, and his family on the passing of his mother," the top American envoy said in a statement.

"Such a loss is especially hard coming on the eve of Nowruz, traditionally a time when families gather together in joy and hope," he added.

Rouhani's mother Sakineh Peivandi died in a Tehran hospital on Thursday at the age of 90, just as the country was celebrating the Persian New Year.

Kerry is joining other U.S. partners -- Britain, France, Russia, China and Germany -- for stepped-up nuclear talks with Iran in the Swiss city of Lausanne, with a view to mapping out the outline of a deal over Iran's controversial nuclear program by the end of this month.

Hossein Fereydoun, Rouhani's brother and a presidential special adviser, was also participating in the talks.

"We share in his grief and that of his brother," Kerry said of Rouhani, "And we keep their family in our thoughts."

In a video message released on Thursday to mark Nowruz, U.S. President Barack Obama called on Iranian leaders not to miss a "historic opportunity" to reach a reasonable nuclear deal, warning that otherwise such a moment "may not come again soon." Endi