Engineers are responding to “severe” power cable damage that has caused mass disruption to Watford Junction trains.

National Rail has confirmed that the overhead wires near Hemel Hempstead have been damaged this morning (December 21).

Because of this, trains running through Watford between Milton Keynes and London Euston/East Croydon are “severely disrupted”.

Eight of the next 10 departures (from 1.30PM onwards) from Watford Junction are set to be disrupted with four of these being cancelled outright.

“Major disruption is expected to last until 5.30pm”, National Rail added. “Our engineers are responding to a fault with power cables affecting services.

“Please check before you travel.”

Replacement buses are running between Northampton and Milton Keynes as well as Milton Keynes to Watford junction.

Ticket acceptance is in place on the London Overground, where the TfL trains are still running, and via other services depending on the operator the ticket is with and the journey it is for.

Watford to London commuters may also wish to use the Abbey line to St Albans to connect with services to London St Pancras there, and LNR ticket acceptance was in place for this. Update: Abbey line journeys have been replaced with buses today due to a fallen tree.

Southern Rail has warned that its trains heading from East Croydon or Selhurst towards Watford Junction or Hemel Hempstead may terminate at Shepherds Bush, and return south from there.

Train users may be entitled to compensation provided they keep their ticket and make a note of their journey.

Update (1.30pm):

Some passengers north of Watford on journeys to London Euston have reportedly been stranded on trains.

London Northwestern Railway has issued advice saying "If you are on a stranded train, please follow all instructions from the onboard crew."

Update (5pm): 

Lines have reopened but disruption is now expected until 7pm.