US President Barack Obama unveiled has sanctions against those who help Syria and Iran track dissidents through cell phones and computers.

He also said he would keep adding pressure on both governments to prevent mass atrocities.

In a somber speech at the United States Holocaust Memorial Museum, Obama said Damascus and Tehran were monitoring the social media tools that allowed democracy campaigners to organize rallies in the Middle East to plot attacks against opposition groups.

'These technologies should be in place to empower citizens, not to repress them,' he said, announcing new asset freezes and visa restrictions against Syrian and Iranian agencies as well as those helping them access surveillance used to plan violence.     
Obama, a Democrat, is under election-year pressure to do more to prevent Iran from acquiring a nuclear weapon and stop Syrian President Bashar al-Assad from waging attacks that have killed more than 9,000 people over the past year.     

'We will keep increasing the pressure for the diplomatic effort to further isolate Assad and his regime,' he told the audience of about 250 people, including Holocaust survivors, government officials and diplomats.

But Nobel Peace Prize winner Elie Wiesel, in pointed remarks introducing the president, warned it may be 'almost too late' to stop their abuses. - Reuters