A humpback whale that died after swimming into the Thames was hit by a ship, the Zoological Society of London (ZSL) has said.

However, it is not clear whether the wound on the juvenile female was inflicted before or after its death.

British Divers Marine Life Rescue, which helps marine animals in distress around the UK, said it had found the dead whale just after 5pm on Tuesday in the Greenhithe area of Kent.

Rob Deaville, ZSL’s cetacean strandings investigation programme project manager, said ZSL experts were working with the Port of London Authority to carry out a postmortem on 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.

“ZSL’s CSIP team will be carrying out the postmortem this evening to learn more about the reasons for the whale’s death and why it entered the Thames.”

Humpback whales are rarely stranded around the UK coast, with just one or two incidents recorded on average each year. However, this is the fifth humpback to be recorded stranded in the UK so far this year.

Two other humpback whales recorded in the Thames and wider Thames estuary region, in 2009 and 2013, both died.