Pakistanis are more likely to be turned down for visas to visit the UK than any other nationals, according to British Home Office statistics obtained by the BBC.
The figures showed some 41 percent of applications for family visitor visas from Pakistan were rejected in the last year.
Bangladeshis were the second least successful with a refusal rate of 31 percent but the figure for India was just 14 percent.
Sarah Teather, Liberal Democratic MP for Brent East, blames discrimination by the Home Office, but the government denies this.
Tougher controls are thought by some people to be due to growing controversy over immigration, and fears visitors are staying beyond their visa and disappearing into the UK.
The Home Office rejected accusations of discrimination and said it refused applications only when they were unsatisfactory.
Applicants must show they will leave the country when they are supposed to and have sufficient funds for their stay, it added.