Passengers wait to check in with a pile of luggage at Heathrow Airport terminal four, London, (File photo)

Strict new security measures on hand baggage came into effect across European airports Monday.  The new rules limit the amount of liquids people may take on board planes.  

Throughout the 25-nation European Union and Norway, Iceland and Switzerland, air travelers must comply with new security measures at airports.

The new compulsory rules are aimed at standardizing measures in Europe put in place after London authorities said in August they had foiled a plot to bomb flights bound for the United States.

Large posters at airports explain the new rules to passengers. Air travelers must now pack water, perfumes, toothpastes and other liquids into small plastic bags before going through airport security checkpoints.

Passengers are allowed to carry on one re-sealable transparent plastic bag that is a maximum size of 1 liter. Liquids carried on the plane in the plastic bag must be placed in separate 100 ml (3.5 fl oz) containers.

At Rome's Fiumicino Airport, airport authorities warned passengers to turn up for their flights well ahead of time, as long lines formed. Many passengers were still unclear about the new rules.

Vitaliano Turra', director of Italy's civil aviation authority, says many still carried containers with shaving cream and creams whose size exceeded the limits allowed.  The new rules do not affect liquids packed in checked luggage or drinks and perfumes bought at airport shops after passengers cleared security.

Passengers are still allowed to carry medicines and "dietary requirements," such as baby foods, in their hand luggage but may be asked to prove that the items are needed.

At security checkpoints, passengers must remove jackets and coats and take their laptop computers and other large electrical devices out of their hand luggage, to be screened separately.

New restrictions on the size of carry-on luggage will be introduced in April.