BERLIN, Sept 21 (Reuters) - Some of Europe's biggest

airports, including the region's busiest Heathrow, raced on

Sunday to restore normal operations to automatic check-in

systems after disruption caused by hackers a day earlier.

The hacking incident hit check-in and boarding systems

provider Collins Aerospace, owned by RTX, disrupting

operations on Saturday at London's Heathrow, Berlin Airport and

in Brussels, where passengers faced long queues, dozens of

cancellations and delays.

Disruption had eased significantly by early Sunday despite

some continuing delays, airport officials and data showed, while

regional regulators said they were investigating the origin of

the hacking incident.

The disruption is the latest in a string of hacks to hit

sectors from healthcare to autos. A breach at carmaker Jaguar

Land Rover halted production, while another caused Marks &

Spencer ( MAKSF ) losses in the hundreds of millions of pounds.

RTX called the incident a "cyber-related disruption" and

said it had impacted its MUSE software, which is used by several

airlines. RTX was not immediately available for comment on

Sunday.

Berlin Brandenburg Airport said on Sunday problems persisted

but that it was working with the company to resolve the issue. A

manual workaround is in place and there are currently no major

delays or cancellations, it added.

Brussels Airport said in an update to passengers on Sunday

that the cyberattack was having a "large impact on the flight

schedule", causing delays and cancellations of flights.

Heathrow said early on Sunday work was continuing to recover

from the check-in system outage. It added that "the vast

majority of flights have continued to operate".

An analysis by aviation data provider Cirium said delays at

Heathrow were "low", Berlin had "moderate" delays, while

Brussels had "significant" delays, but that they were

decreasing.