More than 500 kilos of rotting khat leaves are piling up at the court building and police headquarters after already being exhibited as evidence in magisterial inquiries, even though it is so far not illegal to import the plant.

The decaying leaves are attracting insects, which may potentially harm other evidence being stored nearby, sources have told The Sunday Times.

Although legal in the UK, the plant is currently banned across the US, Canada and most of Europe. A Bill banning importation, cultivation and sale of the plant in Malta is currently before Parliament.

From 2006 to the present day, 62 magisterial inquires have been launched at an average cost of €150 each, resulting in a bill of €9,300, which does not factor in the time taken from court experts and magistrates conducting such inquiries.

The baggage belonging to those who have imported the leaves is confiscated by police for the purposes of an investigation, even though the drug is not illegal.

The legality of the drug in Malta was tested in 2009. Although a Somali man was initially convictedfor possessing 14 kilos of khat, he was acquitted on appeal.

This decision has so far been confirmed three times in separate cases by three judges.

In March, 2010, a Hungarian man was also acquitted of illegally importing the plant even though the prosecution had argued his intention was to import the active ingredients and not just the plant.

The plant, Catha edulis, contains the illegal chemicals cathine and cathinone, but one would need an industrial laboratory to extract them.

The leaves have been chewed by east Africans for hundreds of years for their stimulant effect, and the plant plays a big part in the social lives of both men and women. In most cases it is brought to Malta by immigrants from the UK, where it is legal.

The leaves, which have to be consumed fresh, are usually wrapped in dampened banana leaves and newspaper and decompose quite quickly when placed in bags.