The minister was due to meet her counterpart Eamon Ryan in Dublin today to discuss an all-Ireland strategic rail review.
She was asked about rail connectivity in Stormont by Sinn Féin MLA for Foyle Pádraig Delargy.
"Another key development that is needed in the north-west is better rail links between Derry and Belfast. Will you update us on where that is?" asked the Derry representative.
Ms. Mallon responded: "The Member will be aware that I have initiated a number of feasibility studies. One is of Phase 3 of the Derry to Coleraine rail line. That has been completed, and the business case is being worked on.
"A feasibility study for the additional three halts and a half-hourly service will be completed in the summer. Overlaying all that is the all-island strategic rail review, which is looking at how we can improve existing rail connectivity on the island, where we can have new rail links, the role of rail for freight and rail connectivity to our ports and airports."
The minister said she was due to get an update on the review with Minister Eamon Ryan and consultants today. She said she is committed to 'driving it forward'.
"As we have discussed before, there has been historical underinvestment in the north-west, and you can see that most starkly when you look at a map of rail connectivity on the island, so I am committed to doing what I can through working with partners to address that," she said.