LONDON: A 12-year-old Indian-origin girl in the UK has achieved the highest possible score of 162 on a Mensa IQ test, outwitting physicists Albert Einstein and Stephen Hawking.

Lydia Sebastian from Essex has joined the one per cent of all entrants to attain the highest mark in the Cattell III B paper supervised by Mensa, the society for people with high IQs.

Lydia completed the paper with minutes to spare at the sitting at Birkbeck College, London during her school holidays.

"At first, I was really nervous but once I started, it was much easier than I expected it to be and then I relaxed," said Lydia.

She said the paper challenged her language skills, including analogies and definitions, and her sense of logic, the Guardian reported.

Lydia's father, Arun Sebastian, a radiologist at Colchester general hospital, said his daughter "had looked at the websites for the IQ tests herself and had shown an interest in them and talked to my wife about them."

She has read all seven of the Harry Potter books in the series three times.

Lydia is talented in other areas and has been playing the violin since aged four. She starting talking at the age of just six months, her parents said.

Lydia joins Nicole Barr, a 12-year-old from Harlow, Essex, as well as Aahil Jouher, a 10-year-old from Blackburn, in achieving perfect Mensa scores this year.

Cattell III B has 150 questions, often assessing comprehension through passages of texts, while the maximum score that can be achieved is 161 for adults, and 162 for under-18s.

Both Hawking and Einstein are thought to have an IQ of 160.

Mensa is believed to be the largest and oldest high IQ society in the world. Membership is open to anyone who can demonstrate an IQ in the top 2 per cent of the population, measured by a recognised or approved IQ testing process.