The European Commission is stepping up pressure on drug companies it suspects of using illegal sweetener deals to protect their patents and prevent cheaper generic drugs from entering the market.

Just three weeks before she is due to stand down as European Union Competition Commissioner, Neelie Kroes has asked several European companies to supply her staff with copies of their patent settlement agreements.

The commission did not divulge the identities of the companies it had targeted. But several confirmed they had been contacted and asked to provide documentation, including …