Workers on Virgin's East Coast rail line are to be balloted for industrial action in a dispute over pay.
Members of the Rail, Maritime and Transport union (RMT) will vote in the coming weeks on whether to launch a campaign of action.
The move follows a vote in favour of strikes by RMT members on Virgin's West Coast route, also in a dispute over pay.
The RMT accused Virgin of trying to create a "two tier" workforce on the East Coast by offering new employees no sick pay for the first 12 months and an inferior sick pay scheme after that, as well as imposing a rejected pay offer.
General secretary Mick Cash said: "We will not stand by while Virgin East Coast attempt to impose a two tier workforce with different terms and conditions for our members.
"The pay offer was put to our members and they rejected it by a large majority. Instead of negotiating the company has sought to impose the offer."
A Virgin Trains spokesman said: "We have not yet received formal notification from the RMT but we are disappointed if this is true.
"We have offered members what we believe is a very fair 3.2% pay increase and we remain open to discussions with them."