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Emergency services were called out to reports of "skeletal remains" in a river.
Kent Police and Kent Fire and Rescue Service attended the scene at the Riverside Country Park in Gillingham earlier today after a member of the public spotted bones sticking out of the mud.
Pictures showed crews using a ladder to reach from the shore to a point further out into the River Medway estuary.
A passerby was earlier told the area had been sealed off after the discovery while efforts were made to identify whether the bones were human.
A police spokesman said: "Kent Police was contacted on the evening of Sunday, January 1, and it was reported that bones had been seen in the River Medway near Lower Rainham Road.
"Officers attended at low tide with Kent Fire and Rescue Service and the bones were recovered.
"Following examination, they are believed to be animal remains."
The fire service remained at the scene for six hours after arriving at 9.30am on Monday, January 2.
A spokesman added: "Kent Fire and Rescue Service was called to assist Kent Police at Riverside Country Park in Rainham, Gillingham.
"Two fire engines, a height vehicle and the water safety unit attended."
The estuary stretches between Gillingham and Hoo and is home, further along near where the Swale meets the Medway, to the famed Deadman's Island.
The small island is a site of special scientific interest due to nesting bird populations but in 2016 was also found to be the resting place of 200 men and boys believed to have died from disease aboard prison hulks moored in the area in the 19th century.