"We're disappointed that the RMT Union is intending to organise a [strike] ballot. We will continue to progress the constructive discussions that are taking place over this matter with the RMT and our staff representatives."
The Rail Maritime and Transport Union (RMT) is balloting its members in a row over bonus payments for staff working during the Olympics.
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Drivers belonging to the RMT union are due to walkout at 9.30pm on Saturday in a dispute over a sacked colleague.
A new opinion poll gives the party an increased lead at the expense of the Greens.
The Rail Minister said it was not a matter of crowd control but passengers "trying to get home after a long day at work".