A humpback whale which died a few days after it was seen swimming in the River Thames was hit by a ship, according to the Zoological Society of London (ZSL).
But it is not clear if the wound on the juvenile female was inflicted before or after its death, a spokesman said.
The mammal was spotted motionless on mudflats along the river at Greenhithe on Tuesday afternoon by the British Divers Marine Life Rescue (BDMLR).
The BDMLR said the whale’s death was “not wholly unexpected”.
Rob Deaville said ZSL experts from the UK Cetacean Strandings Investigation Programme were working with colleagues from Port of London Authority to carry out the post-mortem examination of the whale.
“From initial examinations ZSL can confirm the humpback whale is a juvenile female and has a large wound indicative of a ship strike, but it is currently unknown whether this was inflicted before or after the whale’s death,” he said.
The BDMLR had said previously the creature likely arrived because of a navigational error, possibly during the recent high spring tides.
Humpback whales are rarely stranded around the UK coast, with just one or two recorded on average each year according to the ZSL. However, this is the fifth one recorded so far this year.
Two other humpback whales which have previously been recorded in the Thames and wider Thames estuary region, in 2009 and 2013, both died.