The 48,800-dwt Omega (built 2004) collided with the 46,000-dwt Mirabella (built 1997) 16 nautical miles north of the estuary of the Yangtze River, according to cargo claims specialist WK Webster, according to TradeWinds.
Both ships are understood to have water ingress. The Marshall Islands-registered Omega is reportedly in danger of sinking as a result of damage to its number five cargo hold.
The Cook Islands-registered Mirabella is loaded with about 45,000 tonnes of iron ore and heading from Tuticorin, India, to Taicang, China.
All crew are understood to be safe.
The Mirabella is managed by Lebanon-based Safe Sea Services and the Omega by Turkish company Gamma Shipping. The companies have been contacted for comment.
Both vessels have protection and indemnity cover placed in the fixed premium market outside the International Group of P&I clubs.