Condoleezza Rice on Sunday paid an unannounced visit to Baghdad in an apparent effort to show support for the government of Nouri al-Maliki as its showdown with the radical Shia Sadrist movement intensified.

The US secretary of state’s visit came shortly after heavy clashes in the Iraqi capital in which 20 militants were reported killed, and the day after Moqtada al-Sadr, the movement’s leader, threatened open insurrection against the government.