An Easyjet spokeswoman stressed there was no danger to passengers, who were not told about the incident.
She said the light aircraft, which was on its was back to Germany after delivering car parts for Vauxhall, would not have been visible to the naked eye as it was around two miles away.
JLA confirmed the incident, which happened just outside Liverpool airspace, was very rare.
It is officially classified as a “loss of separation” incident, rather than a near-miss.