This is the second time that the European Commission has halted its scrutiny. The previous deadline for its decision was March 25, set after Illumina provided remedies in a bid to address its concerns about the deal.

Announced in September 2020, the deal would give Illumina access to Grail's flagship Galleri blood test used to diagnose cancers at early stages when the disease is easier to treat.

The EU competition enforcer stopped the clock on the deal on Thursday, according to a filing on its website.

(Reporting by Foo Yun Chee, Editing by Louise Heavens)