The European Commission has been urged to state whether it will allow so-called 'megatrucks' onto European roads.
Leading a debate on 15 January 2013, the chair of the Transport Committee, Brian Simpson, said there could be a detrimental effect on the environment, and claimed that the infrastructure of many European countries could not cope with larger lorries.
Megatrucks - sometimes dubbed "road trains" - can be over 25 meters long and weigh up 60 tonnes. Countries such as Germany have introduced trials to allow them to use certain parts of the road network, despite fears from some campaigners that they are a safety and environment risk.
Legal questions were raised earlier in the year over whether the Commission had the right to alter the maximum size and weight of lorries operating on EU roads, without consulting the European Parliament.
Mr Simpson said he could not accept that "something like this can be decided on an arbitrary basis" and demanded that changes be subject to the co-decision procedure, giving MEPs full legal powers.
Mr Kallas said that changes to weights and sizes of lorries were technical issues, but that he "respected the committee's opinion".
He insisted that the introduction of megatrucks was a subject for national governments.
He has previously admitted that there is nothing to stop neighbouring countries from allowing mega trucks to cross each other's borders, but has said there would be no EU-wide legislation.
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on the use of simultaneous interpretations, on the European Parliament's website.