Police seized golf balls and darts from United's fans

Police are investigating whether Manchester United fans deliberately arrived late to Tuesday night's Carling Cup semi-final first-leg tie against local rivals City with the aim of smuggling weapons, including golf balls and darts, into Eastlands in the rush.

Both potential missiles were seized from United fans outside stadium, where 18 fans – 11 United, six City and one neutral – were arrested. United fans ripped up seats to throw at the City contingent and police officers were pelted with bottles by fans from both sides. Greater Manchester Police (GMP) made arrests for various public order offences, though CCTV cameras have not identified which fan was responsible for throwing a plastic cigarette lighter at United's Patrice Evra.

The GMP match commander, assistant chief constable Ian Hopkins, said the late arrival of dozens of United fans led police to establish a cordon to prevent crushing and serious injury. City are also facing questions over the disorder. The Football Association's crowd control adviser was at the match and will be asking the home club for their observations on the Evra incident.

The crowd trouble creates concerns about the second leg of the semi-final, which takes place at Old Trafford on Wednesday with the tie delicately balanced at 2-1 in City's favour. The tension between fans at the match was exacerbated by Gary Neville's hand gesture at Carlos Tevez after the Argentine striker's equaliser and it is understood that the FA will remind the players of their responsibilities ahead of the second leg. Neville was told by United's advisers yesterday that he should expect a fine after what seemed to be improper conduct four months after he had been warned as to his future behaviour following his taunting of City fans at Old Trafford. But last night the FA were still looking for conclusive evidence on which to base a case.

The City defender Pablo Zabaleta suggested that Neville had helped fire up Tevez by declaring before the game that United were right to release the Argentine because his financial demands were too high. "He wanted to prove a point," Zabaleta said. "Some United player was talking about Carlos before the game, but he showed in the game that he is a top-class player. After that performance and his goals, nobody can say anything about him now."

There was more evidence of the underlying financial predicament facing United when their parent company revealed overall debts had swelled to £716.5million in their latest accounts. Red Football Joint Venture Ltd, which is owned by the Glazer family, filed accounts for the year ending 30 June 2009 showing their overall debt has gone past £700m for the first time, increasing by £17m from £699m.

The biggest rise has come in the payment in kind (PIK) loans, which typically have a higher interest rate, which show a £27m increase to £202m. The overall debt figure, not contained in the prospectus for a £500m bond issue released last week, illustrate why the Glazers are so keen to raise cash through bonds to reduce the interest on the debt. United's wage bill rose by a mere 1.7 per cent to £104m, less than a week after City revealed their's had soared by 52 per cent from £54.22m to £82.63m and is expected to overtake their local rivals this year.

The City manager, Roberto Mancini, expects Patrick Vieira to be fit for next Wednesday's second leg, with an FA Cup debut at Scunthorpe on Sunday a possibility.