The outage affected services in both directions between London St Pancras International and Paris Gare du Nord, with passengers unable to clear passport control for around four hours.
The Home Office on Thursday evening claimed the issue had been resolved, adding work was under way to fully restore services. Eurostar has apologised for the disruption.
It follows a national eGate failure on Tuesday 7 May, which impacted arrivals at all major UK airports and saw Border Force officials resort to processing passengers manually.
Speaking in the House of Commons the following day (8 May), Labour’s shadow Home Office minister for security Dan Jarvis said the outage "raised questions" about the UK’s readiness to comply with new EU border rules set to take effect later this year.
In addition, the latest issue comes after a failure of the system in April and almost exactly a year after another national eGate outage over the late May bank holiday weekend.
