A fallen tree is blocking the main railway line between Swansea and Llanelli.
Lines in both directions were reported as being blocked at around 3 30pm on Tuesday, August 25.
National Rail Enquiries said that because of the tree blocking the tracks, trains running between Swansea and Llanelli "may be cancelled or delayed by up to 90 minutes".
The expectation is that the disruption will continue until 5pm.
Replacement road transport is available for passengers travelling between Swansea and Llanelli in both directions, with the route going via Gowerton.
Storm Francis is expected to batter Wales for the rest of the day and into the early hours of Wednesday as travel chaos is caused by fallen trees and flooding.
You can follow all the latest updates on the storm here.
There have been widespread reports of flooding and damage as winds of up to 70mph sweep across Wales. Residents and businesses in Neath found themselves flooded for the second time in nine months on Tuesday.
Power cuts, cancelled train services and closed roads have also resulted from the high winds and rain and speed limits are in place on the Prince of Wales Bridge and M4 Briton Ferry bridges.
