Election counts should be conducted solely in English, the Electoral Commission has said.
Its advice came in a report on chaos at the delayed election count at Tower Hamlets LBC in May.
The commission is due to publish a wider report on allegations of voter intimidation that arose in the contest where Lutfur Rahman (Ind) defeated Labour’s John Biggs for the elected mayoralty.
The commission found slow admission of count staff and others entitled to attend caused a two-and-a-half-hour delay that could not be caught up, as insufficient staff were on duty.
Its report said: “plans for the management of the verification and count on Friday 23 May… proved inadequate for the number of ballot papers to be counted.”
Commission chair Jenny Watson said: “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 said the returning officer John Williams should publish a plan for conducting the 2015 general election by December 2014.
Communication between counting staff and others including counting agents should be conducted solely in English to ensure transparency, the commission said.
Those attending should “commit to behaving according to the rules set out in advance by the returning officer”, it added.
Mr Williams said: “The elections were hard-fought and intensely scrutinised. Many additional measures were introduced locally, in discussion with the Metropolitan Police and with the support of the Electoral Commission, to combat fraud, regulate the conduct of participants and build trust in the electoral process.
“These added to the complexity of the elections in Tower Hamlets and the duration of the count, but the overriding aim of a free and fair election was achieved.
“I welcome the report’s recommendations and look forward to developing our plans for future elections in Tower Hamlets.”
Mr Rahman’s re-election is already the subject of a legal challenge by a group of local voters.
Meanwhile, accountants from PwC have asked for more time to report to the government on alleged impropriety in the borough.
Communities secretary Eric Pickles sent in investigators in April to probe allegations of misdirection of grants and report back by 30 June.
The firm told DCLG: “While it should be recognised that the council has provided substantial amounts of information and documentation, there have been in some cases considerable delays in its doing so and a number of requests for information and documentation that is potentially significant to the inspection remain outstanding.”
It now expects to report in the middle of this month.
DCLG said the inspection’s costs were likely to be up to £1m, which it would seek to recover from Tower Hamlets.