A beluga whale, which was has been swimming in the Thames Estuary near Gravesend for almost a week, appears healthy and is not in any immediate danger, officials say.
Members of the public have flocked to watch the mammal, affectionately dubbed "Benny the beluga", since it was first spotted swimming in the river on 25 September.
The whale was again sighted on Sunday morning close to Gravesend and is not currently travelling to busier parts of the river.
It is "swimming up and down" the estuary and over "six continuous days has, more or less, stayed just east of Gravesend," said Port of London Authority spokesman Martin Garside.
The animal appears to be feeding well and is outwardly healthy.
Officials from the Port of London Authority have urged river users to steer clear of the whale, so that it does not become distressed.
“We thank river users for their consideration in avoiding the area, and ask them to continue to do so," said Tanya Ferry, the organisation's environment manager.
Groups monitoring the whale want to avoid a repeat of an incident in 2006 when a young, bottlenose whale swam up the Thames and into London, passing Parliament on its way.
"People took small boats out and got quite close to the whale," Mr Garside added, "and we don't want that. We're asking that people observe the beluga whale from the shore."
The 2006 Thames whale could not be saved and died when rescuers attempted to lift her out of the water.
Officials hope that the animal will eventually return safely home but cannot predict how long it will remain in the Thames.
"It's remarkable and there's no immediate crisis," Mr Garside said. "But even so, this whale is far away from home."
Beluga whales live near the Arctic and are traditionally found around the coastlines of northern Scandinavia, Russia, Alaska and Canada.
They do occasionally frequent estuaries in their native environment and are not prone to becoming stranded.
