Kent, Surrey and Sussex rail chaos blamed on engineering works
Overnight engineering work has been blamed for train cancellations that caused chaos south of London.
Thousands of commuters were stranded as Southern Rail cancelled all services between Redhill, Reigate and Tonbridge, as well as Haywards Heath and Lewes.
Southeastern cancelled trains between Strood and Paddock Wood and services between Swanley and Faversham and Tonbridge and Hastings were delayed.
Network Rail apologised, saying de-icers and route provers could not run.
Ice on rail
Tom Tugendhat, MP for Tonbridge, Edenbridge and Malling in Kent, said he had written to Network Rail to demand answers over the chaos, tweeting that Southeastern and Southern should have responded better.
Southeastern, which also cancelled services between Ashford International and Maidstone East, blamed poor rail conditions for the disruption.
Passengers were told they could use tickets on High Speed services at no extra charge.
Southern said ice on the conductor rail meant trains could not take power, causing cancellations, but added Great Western diesel trains were running and accepting its tickets.
BBC News producer Charlie Rose tweeted that services were at a standstill on the Hastings line and posted a picture of stranded commuters in the cafe at Etchingham station in East Sussex.
Network Rail said passengers and train operators had a very difficult morning and did not receive the level of service people expect.
"While our de-icing train fleet ran overnight and our rail heaters were all on and working, this still hasn't been enough to prevent delays," said route managing director Alasdair Coates.
"We are investigating what further action we can take to mitigate the problem of ice forming and making it unsafe for trains to run."
Southeastern apologised for the delays, including further disruption caused by a broken rail at Kidbrooke, south-east London.
"We encourage all passengers who were delayed by 30 minutes or more to claim compensation under our Delay Repay scheme," it said in a statement.
Engineering work was also blamed for disruption when more than 20 rush-hour trains into London from Kent did not run on 28 January.
Services between Ashford and London were disrupted when lines were left without power because of overrunning engineering work.
Southeastern said delays caused by a power loss between Maidstone and Swanley were down to engineering works that did not finish on time.
In January Southeastern blamed "bright sunlight" for delays to services through south-east London.