A six-year-old girl has become the latest victim of swine flu, taking the number of UK deaths linked to the virus to 16.
Chloe Buckley, from north-west London, died on Thursday at St Mary's Hospital in Paddington.
A post-mortem examination will be carried out to determine if she had any underlying health conditions, Dr Simon Tanner, from NHS London, said.
It comes after the first British patient without underlying health problems died on Friday after contracting swine flu.
The patient, from Essex, died in Basildon.
Doctor Tanner, NHS London's regional director of public health, said: "We would like to extend our deepest sympathies to the family at this difficult time as they come to terms with their loss."
He said Chloe had contracted the virus in the UK.
He described her death as "sad" and added: "It will probably not be the last that we have in this pandemic."
Earlier, it was disclosed that the swine flu virus sweeping the country had reached Downing Street. It is understood that Gordon Brown's adviser on climate change, Michael Jacobs, has been infected.
It is thought that he may have contracted the virus during a recent visit to Mexico where the global outbreak originated. He is not thought to have had any direct contact with the Prime Minister since developing the symptoms two weeks ago.
