A voting watchdog has branded management of mayoral, European and local elections at Tower Hamlets 'inadequate' following count delays in May.

The Electoral Commission ordered all Tower Hamlets counting staff and officials to speak only English at future counts in order to avoid deception.

According to the independent watchdog, the local authority allocated inadequate resources to the vote count and its subsequent verification. Delays in allowing access to the vote count and verification venue meant procedures were delayed by two and a half hours.

According to the Commission, not enough staff were on hand to recover from initial hold-ups or manage the number of ballot papers requiring verification within the returning officer's timetable.

Jenny Watson, chair of the Electoral Commission, said: 'With the May 2015 General Election fast approaching it is vital that everyone involved in the elections in Tower Hamlets learns from the experience of the 2014 elections so voters and campaigners in Tower Hamlets can have confidence in the administration of future election counts.

'We will be monitoring the returning officer's response closely over the coming months and if we are not satisfied that sufficient progress has been made by September 2014 we will make clear what more needs to be done.'

The Commission recommended instructions for all those attending vote counts in Tower Hamlets be undertaken in English only. Its report said: 'Several submissions also expressed concern about some counting agents and other attendees talking to count staff in Bengali, which meant that other observers could not understand what had been said.'

Tower Hamlets returning officer John Williams said: 'I welcome the report's recommendations and look forward to developing our plans for future elections in Tower Hamlets, learning the lessons from May 2014 and working in partnership with the Commission and all stakeholders locally.'

The news came as communities secretary Eric Pickles announced the extension of the investigation into the council's mayoral administration.

Speaking to the House of Commons, Pickles said: 'The investigators, PricewaterhouseCoopers, have informed me that the council has considerably delayed the investigation by delaying the provision of key information or by simply not providing it at all. This is not acceptable.'

'I am consequently extending the period for PwC to report. The costs will be met by the council. Whether the council likes it or not, this investigation will be thorough and comprehensive. I will update the House in due course.'