Qualcomm ramped pressure on US authorities to ban the importation of some iPhone models, arguing a recent software update designed to avoid patented technology undermined an earlier judgement, Reuters reported.

The latest comments, made in a filing to the US International Trade Commission (ITC), are part of a lengthy legal battle between the two across a number of markets.

In this specific case, the ITC is reviewing a decision made in October to allow the continued importation of specific iPhone models despite finding Apple had infringed a Qualcomm patent related to power saving technology.

Earlier this month, news broke Apple had implemented a software update which avoided using Qualcomm patented technology. However, the effectiveness of the change would not be fully proven until six months after implementation. Additionally, the smartphone manufacturer argued it needed time to sell existing stock.

However, in its latest filing Qualcomm argued Apple’s admission it had deployed a fix undermined the judge’s original decision not to impose an import ban.

The ITC’s final decision, which was originally expected today (20 February), is now scheduled to be made by the end of March. Qualcomm has already won similar cases in China and Germany.

Apple and Qualcomm are also due back in US courts in April, when authorities are scheduled to hear a complaint related to Qualcomm’s licensing practices.