A waste-collection bin left in the water has amassed a collection of polystyrene, cigarette butts, and plastic pens after being left in the sea for just under two weeks.

A spokesman for the eNGO Zibel said the exact amount of waste collected had not yet been determined, but it was "above the average" amount expected.

In fact, while seabins abroad are emptied twice a week, the seabin left at the Marina di Valletta at Pieta' had to be emptied daily. 

"Seabins usually collect around half a ton of waste a year, but we wouldn't be surprised if the one in Malta collects around three-quarters of a ton this year," the spokesman said. 

The 'usual suspects' - fishing line, microplastics, plastic bags and bottle caps - had been collected, the eNGO said.

The seabin is a device that moves up and down with the tide, collecting all floating rubbish. Water is sucked in from the surface by a submersible water pump. The water is then pumped back into the marina, leaving litter and debris trapped in the catch bag to be disposed of properly.

Seabins can collect 500kg of waste a year, costing less than €1 a day, Strand Marine operations director Matthew Travers had said.

Read: Rubbish bins being left in sea to scoop up surface waste

Żibel co-founder Andrew Schembri had warned the seabins alone were not enough to clean up the sea, adding that the important thing was to educate people on water pollution.