More are joining Apple's court battle against Qualcomm.

Four iPhone manufacturers have filed a suit against the US chipmaker, alleging it used its market position to charge excessive royalties, Reuters reported Wednesday.

They are Foxconn's parent company Hon Hai Precision Industry, Wistron Corp, Compal Electronics and Pegatron Corp.

The move is a rebuttal to Qualcomm's suit in May, which sought to press the contractors into paying license fees after they refused to do so.

Until earlier this year, Apple paid its manufacturers' Qualcomm royalty fees, so when Apple decided it would no longer pay up, the manufacturers stopped paying that fee.

Apple said it won't resume payment till its problem with Qualcomm -- it brought the chipmaker to court in January, accusing it of unfair licensing terms -- is settled.

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