The European Union imposed new sanctions on the government of Syrian President Bashar al-Assad Monday, a day after more than 30 people died in violence across the country during a continuing crackdown on an anti-government uprising.

EU foreign ministers imposed sanctions on Syria’s central bank and froze the assets of several Syrian government officials. The bloc already has blacklisted nearly 150 other Syrian entities and people.

Sunday’s violence came as the Syrian government held a referendum on a new constitution, portrayed as a step toward democratization.

The new document would create a multi-party system in Syria, which has been governed solely by the Baath Party since 1963, and set presidential term limits. But even if it passes, President Assad will still be very powerful.

Opposition factions called for a boycott of the vote, saying the only acceptable solution to Syria’s crisis is for President Assad to step down.

Western governments rejected the referendum as a farce, but both China and Russia welcomed it Monday.

Throughout the Syrian crisis, Russia and China have blocked the U.N. Security Council from acting against Mr. Assad’s government.

U.S. Secretary of State Hillary Clinton has called the actions by Beijing and Moscow on the Syrian conflict “despicable.”

On Monday, Chinese Foreign Ministry spokesman Hong Lei said China will not accept Washington’s denunciation of other countries.

“The comments by the mentioned American person are totally unacceptable for us. On the Syria question, China has always maintained a fair and objective stance.”

Separately, Russian Prime Minister Vladimir Putin defended the joint veto by Russia and China of a U.N. Security Council resolution condemning Syria for its military crackdown on dissent.

U.N.-appointed investigators estimate the death toll from the uprising at 6,400 civilians and 1,680 army defectors. Syrian officials have said they only took military action when under armed attack from “terrorists.”