Hargreaves Services said it had been working closely with the authorities since the landslip was first detected in mid-February, but had been unable to carry out meaningful work until the tip stabilised.
Rail tracks between Hatfield and Stainforth, near Doncaster, have been lifted, twisted and partially buried by the vast movement of waste coal at Hatfield Colliery, and services to both Scunthorpe and Goole from Doncaster have been suspended.
Instead passengers are being forced to travel on rail replacement bus services, which add at least an hour onto the journey between towns.
Local residents have spoken of safety concerns since the land slip happened and National Union of Mineworkers officials have raised fears that the cost of remedying the problem may lead to the closure of the colliery – which is one of the last deep mines in operation in the country.
A spokesman for Durham-based Hargreaves Services said: “Since the landslip occurred earlier in February, Hatfield Colliery has been working closely with all parties including Network Rail, civil engineering experts, government agencies and Doncaster Council to address the issues brought about by the event.
“Now that the tip has stopped moving, the parties are working towards a solution to restore rail services. The colliery continues to work with Network Rail and provide all possible support.
“The colliery is meeting regularly with the Mayor of Stainforth and the Town Council in order to keep residents informed of progress and discuss any concerns they may have.
“The colliery has continued to operate throughout this period.”
Last week, Network Rail predicted the line would not open until June at the earliest.