The “Rehab” star was first implicated a bribery plot involving her jailed husband Blake Fielder-Civil on Sunday.
Fielder-Civil is currently being held on remand at London's Pentonville Prison and is awaiting trial on a similar charge after he attempted to fix the outcome of his trial for grievous bodily harm.
He is alleged to have assaulted barman James King in June last year, and stands accused of trying to pay off King with $400,000 and a free vacation to withdraw his statement.
But Winehouse is also believed to be involved in the plot, and was arrested on Tuesday afternoon after voluntarily turning herself into police in Shoreditch, east London, for questioning.
The news comes just days after police confiscated her cell-phone records, bank details and computer software, which could provide evidence of the star's alleged involvement in the plot.
Last week, cops also visited the singer's accountants, the prestigious London-based firm Smallfield Cody, in an attempt to track all of her financial dealings.
However, as WENN went to press, Winehouse is yet to be charged with any crime.
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