Train delays Manukau and Papakura

The fault happened at Homai about two hours ago. Photo / Supplied

A fault with overhead power lines is affecting Auckland passenger trains on two of city's mainlines as the busy home commute period approaches.

Auckland Transport says the southern and eastern lines are operating at a "20-minute frequency, terminating at Manukau".

The fault happened at Homai about two hours ago.

An earlier tweet from Auckland Transport warned of delays and cancellations on the lines, with busses taking commuters between Manukau and Papakura.

A KiwiRail spokeswoman confirmed trains were halted this afternoon between Papakura and Wiri, because of the fault "with an overhead traction cable".

"The catenary wire, which is used to hold all of the other wires in place, broke near Manurewa Station," she said.

"The exact cause of the fault is still unclear and power to both tracks on that section of the line was turned off while KiwiRail staff were on-site.

"The cable has now been repaired and passenger and freight services will resume running on the North Island Main Trunk line south of Westfield."