Thailand is to ban smoking on some of the country’s most popular tourist beaches, with the prospect of up to a year in prison for those caught lighting up, according to reports by local media.

The move follows a recent survey of litter on Patong beach, Phuket – visited by millions of foreign tourists each year – which found an average of 0.76 cigarette butts per square metre in a sample area, which would amount to 101,058 butts on the 2.5km-long stretch of sand.

The survey was undertaken by the country’s department of marine and coastal resources, which described it as a “serious problem”. Discarded cigarette butts accounted for a third of rubbish collected by the department.

“Cigarettes have a direct effect on the natural environment,” director general Jatuporn Buruspat told the Phuket Gazette.

“The butts clog the drains contributing to floods. When the cigarettes stay under the beach sand for a long time, it also negatively affects the eco system. And then when the chemicals from the cigarette butts reach the water, it also releases cadmium, lead, arsenic and some acid from insecticide which are poison to the natural food chain.”

The ban, which will come into play in November, will affect 20 beaches including Patong, Koh Khai Nok, Koh Khai Nai (Phuket); Hua Hin, Cha-Am, Khao Takiab (western province of Prachuap Khiri Khan); Pattaya, Jomtien, Bangsaen (eastern province of Chonburi) and Samila (Songkhla city).

After a trial period, the ban is expected to be enforced on all Thai beaches, as well as on passenger and tourist boats, to tackle the problem of butts damaging the underwater environment.

Anyone found to be breaking the law will face one year in jail or a maximum 100,000 baht (£2,285) fine, or both.

The Bangkok Post also reported the news, adding that Thailand has the sixth most rubbish-strewn areas of sea in the world.