Pakistan, Jan. 27 -- A US naval strike group led by an aircraft carrier has deployed to Middle Eastern waters, the United States said Monday, as Tehran warned it was ready to hit back at any American attack launched in response to a crackdown on anti-government protests.

A US-based rights group said on Monday that it had confirmed the deaths of nearly 6,000 people in the wave of protests suppressed by Iran's security forces, but emphasised the actual toll could be several times higher.

The protests started in late December, driven by economic grievances, but turned into a mass movement against the Islamic republic, with huge street demonstrations for several days from January 8.

But rights groups have accused authorities of quelling th...