Almost a third of prisoners at Wormwood Scrubs are foreign nationals, with the majority of convicts from Europe, new figures reveal.
Of the 1,258 people jailed in the Hammersmith and Fulham prison, 396 are not British nationals.
The findings make the Scrubs the THIRD highest prison for foreigners, with a rate a staggering three times higher than the average for men's prisons in England and Wales.
Excluding two prisons that cater exclusively for criminals who are from abroad, the average for most prisons is around 10%.
Feltham prison in Hounslow also has one of the highest rates, with foreign nationals making up nearly a fifth of the population.
Of the 494 prisoners there, 91 are foreign nationals and is the eleventh highest proportion in England and Wales.
Commenting on west London's criminals behind bars, Glyn Travis, of the Professional Trades Union for Prison, Correctional and Secure Psychiatric Workers, previously said: "The prison system is bursting at the seams.
"The government needs to engage with other countries to take ownership of their offenders so the Ministry of Justice can target offenders and address offending behaviour."
Most common nationality revealed to be Eastern European
The figures, obtained by Trinity Mirror, showed the most common nationality was Polish.
Around 1,012 were from the eastern European country, followed by Irish (745), Romanian (674) and Jamaican nationality holders (534).
Britain is said to be spending over £360 million a year to keep non-British nationality inmates in prison.