European Union investigators are widening their investigation into whether drugmakers used unfair tactics to block competition and prop up prices, The Wall Street Journal reports.

In recent weeks, investigators sent questionnaires to drug wholesalers and trading firms, asking them about pharma’s distribution methods, and responsed were due by mid-June, according to the paper. A spokesman tells the Journal that the European Commission has “sent several different sets of questionnaires to different people,” but declined to comment further.

The latest round of questioning broadens an inquiry begun in January, when EU investigators visited pharma offices unannounced and collected documents, the paper reminds us. At the time, Neelie Kroes, the EU’s antitrust chief, said the issue is whether brand-name drugmakers were paying generic rivals to keep their low-cost pills off the market.

In the latest questionnaires, the EU is asking about the distribution methods drugmakers use in Europe, and whether they are blocking competitors from distributing meds, according to the paper.

Heinz Kobelt, secretary-general of the European Association of Euro-Pharmaceutical Companies, tells the Journal that EU investigators sent him a questionnaire in mid-May asking whether drugmakers were using litigation or other tactics to thwart parallel trade. Drugmakers oppose parallel trade because it undercuts their direct sales, but wholesalers say it benefits consumers by lowering prices.

Kobelt says the questionnaire asked for his group’s views on so-called direct-to-pharmacy distribution channels, which Pfizer. and AstraZeneca have recently established in the UK. Direct-to-pharmacy channels differ from traditional distribution in that the drugmaker pays wholesalers a set fee to deliver goods to pharmacies, rather than selling to the wholesaler, the Journal explains.

Drugmakers say the approach helps them keep better control over their goods and prevents counterfeit medicines from getting into pharmacies. Wholesalers say drugmakers are trying to prevent parallel trade, a charge the companies deny.