Rail services between Great Malvern and Hereford will remain affected until 6pm this evening (Monday).
Network Rail said it was due to 'unforeseen circumstances' impacting its workforce.
Services have been unable to run between Great Malvern and Hereford since Sunday evening.
As a result, West Midlands Railway services between Birmingham New Street – Hereford will run between Birmingham New Street – Great Malvern only.
Rail replacement buses will be running between Great Malvern – Hereford until 6pm.