The amount of litter left strewn on Scottish beaches hiked by two-thirds in a year, according to a new survey.

Research by the Marine Conservation Society (MCS) found that an average of 2999 pieces of rubbish were left per kilometre of Scotland's beaches in 2015, compared to 1803 in the previous year.

In total, 45,815 items were collected from 75 beaches across Scotland during the MCS Great British Beach Clean last September.

High levels of all types of litter were found to have contributed to the 66% increase, however volunteers who logged the items found that rubbish classed as "sewage related debris" (SRD) was notably high.

Cramond beach on the outskirts of Edinburgh was found to have the most SRD; items such as wet wipes and condoms, which are flushed down the toilet when they should be put in the bin.

On average, 99 plastic bottles were picked up along every kilometre cleaned at 340 UK sites during the clean-up.

Bottles on Scottish beaches rose by 21.3%, compared to 6.3% in the Channel Islands, 57.2% in England, and 235.3% in Northern Ireland. In Wales they dropped by 39.4%.

MCS is a founding partner of the "Have you got the bottle" campaign, led by the Association for the Protection of Rural Scotland (APRS).

It is calling for a deposit return system (DRS) involving a surcharge being put on drink containers, which would be refunded when the bottles are returned.

Calum Duncan, MCS head of conservation in Scotland, said: "We’re confident that evidence from other countries and a successful trial at Heriot-Watt University shows that a Scotland-wide roll-out of a DRS would lead to reduction in the number of drinks containers that blight our beaches."

He said a recent survey had showed public support for a DRS scheme in Scotland.

Mr Duncan added: "With countries like Germany, where DRS was introduced a decade ago, recycling near to 99% of drinks containers, it’s not difficult to see why support is growing for this proven system."

During last year's beach clean, 1421 volunteers took to Scotland's beaches to pick up litter.

Litter collected from a 100-metre stretch was recorded and compared to data collated in the previous year.