The US special envoy to the anti-IS coalition, Brett McGurk, called today's advance a "milestone" in a statement posted on Twitter.
Brig. Gen. Haider Fadhil of Iraq's special forces confirmed the advance.
Iraq's special forces have largely been leading the push in Mosul's east, while the Iraqi army has been advancing in the north of the city.
Iraqi forces have retaken around a third of the city since the operation began in mid-October.