Transport Secretary Chris Grayling faced a showdown with RMT Union chief Mick Cash as the pair discussed the long-running Southern rail dispute on Friday 21 July.
Cash, the general secretary of the UK's largest transport union, urged the senior Conservative to resolve the row over Driver Only Operated (DOO) trains and the future role of guards on the network.
"It is now accepted that Grayling is directing the Southern dispute so only he can resolve it. Therefore will be asking that he authorise an accessibility guarantee on Southern, which will then allow me to put back a positive report to our NEC," Cash said.
"The union will also be urging him to allow for negotiations to take place to end the Northern Driver Only dispute where we have been told DFT are preventing a deal.
"We will also be asking that he pull back from engineering a Southern-style confrontation across the network, including on South West Trains and Abellio Anglia.
"Today's talks will show us whether he is sincere and bringing fresh thinking to the table or just going through the motions. RMT is entering the talks with positive proposals for resolving the disputes."
The development comes after RMT and train drivers' union Aslef, who have called for improved CCTV systems, suspended their planned strike action on 1, 2 and 4 August in reaction to Grayling's intervention.
A spokesperson for Govia Thameslink Railway, the parent company of Southern, said: "We are delighted on behalf of our passengers. We truly hope that a resolution can be found once and for all."
Liberal Democrat Eastbourne MP Stephen Lloyd added: "Now it's time to turn this breakthrough into a long-term solution. Long-suffering commuters want to see a compromise reached so we can avoid months more chaos and anguish."