Former X Factor judge Tulisa Contostavlos has been arrested on suspicion of supplying class A drugs.
The 24-year-old is alleged to have been caught in an £800 drugs sting by a tabloid newspaper at the weekend.
The N-Dubz singer, who released solo album The Female Boss last year, was set up by undercover reporters at Nobu restaurant and the Dorchester hotel in London.
Rapper Mike GLC, 35, has also been arrested on suspicion of supplying class A drugs.
The arrests come after Metropolitan Police said its officers were "considering" information after the Sun on Sunday alleged Tulisa acted as a go-between in a drug deal by introducing a journalist to an alleged supplier.
Both Tulisa and Mike GLC today attended a central London police station by appointment before being bailed pending further inquiries to a date in late July.
A Met Police spokesman said: "Officers from Westminster have today, Tuesday June 4, arrested two people - a 35 year-old man and a 24-year-old woman - by appointment at a central London police station on suspicion of being concerned win the supply of class A drugs.
Searches by Metropolitan police have also been completed at two residential addresses.
Contostavlos' spokesman declined to comment.
Tulisa was dropped as an X Factor judge last month, with Sharon Osbourne returning to the ITV talent show to replace her.