Hackers have targeted the COVID-19 supply chain, but it is "unclear" if the attempts were successful, IBM said on Thursday.

The warning comes just a day after the U.K. became the first country to approve a COVID-19 vaccine, with several countries already expecting doses.

"Our team recently uncovered a global phishing campaign targeting organizations associated with a COVID-19 cold chain," AFP quotes Claire Zaboeva and Melissa Frydrych, analysts for IBM X-Force, a cyber security working group.

The European Commission's Directorate-General for Taxation and Customs Union was one target, as were energy and IT companies based in Germany, Italy, the Czech Republic among others.

IVM said it was not able to identify the people behind the hacking attempts, but that the precision of the operation signals "the potential hallmarks of nation-state tradecraft."

"Without a clear path to a cash-out, cyber criminals are unlikely to devote the time and resources required to execute such a calculated operation with so many interlinked and globally distributed targets," AFP quotes Zaboeva and Frydrych.