Arriva Trains Wales services will be affected from midnight on Saturday until Tuesday morning Train services will be affected from midnight on Saturday as two days of industrial action by drivers from Arriva Trains Wales begin.
The action called by the Aslef union follows a long-running pay dispute.
There will be no Arriva Trains Wales services on Sunday or Monday and no alternative transport is being provided.
Managers say an offer of a 12% rise over two years is extremely generous.
The union has accused the company of paying Welsh drivers less than their English counterparts.
The 01.50 GMT Fishguard Harbour to Cardiff service on Sunday will be replaced by a bus service but passengers on all other services are being advised to make alternative travel arrangements.
Services on Tuesday are also likely to be disrupted as the network returns to normal.
Peter Leppard, Operations Director for Arriva Trains Wales, said: “Arriva Trains Wales’ senior management and officials from the ASLEF and RMT trade unions have been in talks for many months in an attempt to reach a final agreement on pay and working conditions for train drivers.
“We are extremely disappointed that once again our generous offer has been rejected and that the planned industrial action by ASLEF for 27 and 28 February will go ahead.”
He said the strike would cause significant inconvenience to customers.
An Aslef spokesman said: “We regret the disruption to the service and our passengers but we would not have staged the strike if there had been any alternatives.”
For service updates customers are advised to check the Arriva Trains Wales website – www.arrivatrainswales.co.uk or contact National Rail Enquiries on 08457 48 49 50.
This article is from the BBC News website. © British Broadcasting Corporation, The BBC is not responsible for the content of external internet sites.