Iraq's top Shia cleric said on Friday that it was up to the security forces to make sure protests do not descend into further violence, and urged the government to respond to demonstrators' demands as soon as possible.

"The biggest responsibility is on the security forces," a representative of Grand Ayatollah Ali al-Sistani said in a sermon after Friday prayer in the Shia Muslim holy city of Kerbala.

Sistani also warned against exploitation of unrest in Iraq by "internal and external" forces which seek to cause instability in the country.