The European Parliament has called for a review of regulations that ban airline passengers from carrying liquids past airport security checkpoints to bring on board.
The assembly adopted a resolution calling on the executive European Commission to study the rules and repeal them if "no further conclusive facts are brought forward" about their impact on preventing terrorist attacks.
The EU has limited air passengers to carrying small containers of liquids or gels in sealed plastic bags on board after British authorities last year said they had foiled an attempt to blow up aircraft using liquid explosives.
But duty-free items bought at airports outside the EU became a casualty of the new rules. Passengers who bought whisky or other liquids outside Europe and carried them as hand luggage had to give them up when changing planes in the EU, even though the items would have been purchased after security checkpoints in the departure country.
The European Commission said in July it would apply new measures to allow passengers to keep such products if purchased in countries with security standards that match those of the 27-nation EU.
The resolution expressed lawmakers' concern that "the costs engendered by the regulation may not be proportionate to the added value achieved by additional security provisions", the assembly said in a statement.
The resolution is non-binding and does not oblige the Commission to review the rules. Parliament members cited complaints from citizens about inconvenience and the cost of buying bottled drinks behind security checkpoints as reasons to look at the rules again.
Irish MEP Avril Doyle said there "substantial inconvenience and disruption" was caused to passengers "with no discernable security benefit".
She said the 100 ml limit was "an arbitrary political decision which has no scientific or security basis".
"Ten 100 ml containers legitimately brought through security screening could then be pooled into a 1 litre bottle legitimately purchased airside and brought onboard. So what does the present security restriction of 100ml containers achieve?", she said.