The Delta coronavirus variant that swept the UK has become dominant in Portugal and appeared in clusters across Germany, France and Spain, prompting European health officials to warn further action is needed to slow its spread.

While the new strain, which first emerged in India, still only accounts for a fraction of the total coronavirus cases in mainland Europe, it is gaining ground, according to a Financial Times analysis of global genomic data from the virus tracking database Gisaid. It accounts for 96 per cent of sequenced Covid-19 infections in Portugal, more than 20 per cent in Italy and about 16 per cent in Belgium, the FT’s calculations show.

The small but rising number of cases have raised concerns that the Delta variant could halt the progress the EU has made over past the two months in bringing new infections and deaths down to their lowest level since at least the autumn. “We are in the process of crushing the virus and crushing the pandemic, and we must in no way let the Delta variant get the upper hand,” France’s health minister, Olivier Véran, told reporters at a Paris vaccination centre on Tuesday.

Véran said that 2 per cent to 4 per cent of virus samples being analysed in France were showing as the Delta variant: “You might say this is still low but it is similar to the situation in the UK a few weeks ago.” The FT’s analysis of Gisaid’s data suggests this figure could be higher.