Jeremy Corbyn has said he suffered a black eye and a split lip after a running injury.
Only around one in five trains were running across the country on Thursday because of the walkout by members of the RMT and TSSA unions, causing significant disruption for commuters and travellers.
Speaking to reporters, Mr Corbyn criticised Sir Keir Starmer’s sacking of a shadow transport minister for giving interviews from a picket line last month.
Mr Corbyn said Sam Tarry’s treatment was “very unfair”.
He added: “Sam is a trade union person like me, he used to work for the TSSA, he went on a picket line to support his union and his members. I think to dismiss him from his shadow position was very unfair.”
Mr Corbyn told Mr Tarry after his sacking that he was “very sorry because he was doing a very good job, he was trying to develop a… much better national transport strategy”.
It comes as a union leader warned the rail dispute could be prolonged “indefinitely” as the latest strike by thousands of workers caused travel misery for passengers.
Mick Lynch, general secretary of the Rail, Maritime and Transport union (RMT), called on the Government to end its stance of refusing to get involved in talks over pay, jobs and conditions.
He joined a picket line outside Euston station in London as only around one in five trains were running across the country because of the walkout by members of the RMT and TSSA unions.
Mr Lynch has written to Transport Secretary Grant Shapps, saying: “Your government has made the decision to use taxpayers’ money to bail out private train companies from being liable for revenue lost because of industrial action on the condition the same companies comply with government instructions to hold down pay, cut thousands of safety critical rail jobs, introduce driver only trains and close ticket offices across the network.”
Mr Lynch said the union had calculated that, including the previous and forthcoming industrial action, more than £120 million of taxpayers’ money had been used to “bail out” private train companies to date.
He said: “Using taxpayers’ money to satisfy the anti-union agenda of the Tory party and seek to break the trade unions is shameful and means the dispute will be prolonged indefinitely as the train companies don’t lose a penny as a result of the industrial action and therefore have no incentive to settle the disputes.
“Instead of waging an ideological war against rail workers, millions of voters would rather that the Government allow for a fair negotiated settlement.”