Several thousand people rallied in a town outside Moscow, demanding the closure of a landfill site that has been emitting toxic fumes and calling for the resignation of the regional governor.

The demonstrators on April 1 gathered in the center of Volokolamsk, chanting "close the dump" and holding placards reading slogans such as "protect our children from mass poisoning.”

They also demanded the resignation of local authorities and the governor of the Moscow region, Andrei Vorobyov.

"Our demands haven't changed: We demand that the Yadrovo landfill site be closed and the head of the Volokolamsk district be elected among its residents," the Interfax news agency quoted rally organizers as saying.

Interfax quoted the organizers as saying that 12 protesters were detained by police late on April 1. The agency quoted law-enforcement agencies as saying that Vladimir Glumov, Mikhail Aksel, Mikhail Galyashkin, and Olga Shalina had been detained and transported to the town's police station.

On the eve of the rallies, police detained one of the protest organizers, Artyom Lyubimov, who was charged with a misdemeanor.

Lyubimov’s supporters say the activist, who is accused of disobeying police officers, is expected to go on trial on April 2.

Another activist, Olya Guseva, tweeted several photos showing a city center packed with protesters, many carrying signs.

Pyotr Lazarev, the mayor of Volokolamsk, told journalists that some 6,000 people took part in the demonstration in front of the district administration building.

On March 21, hospitals treated dozens of children in Volokolamsk, a town of around 20,000 people about 120 kilometers west of Moscow, who complained of dizziness and nausea because of fumes from the Yadrovo landfill site.

The incident triggered protests, even after Vorobyov sacked district chief Yevgeny Gavrilov.

On March 29, thousands of residents held a rally demanding that authorities formally declare a state of emergency.

However, authorities said there was no need to evacuate residents or declare a formal state of emergency.

A spokesman for the regional branch of the Emergencies Ministry said that "a state of high alert" had been imposed in Volokolamsk as of March 30, and that monitoring of the environment "will be stepped up" with "non-stop" testing of air quality.

The spokesman also said that local authorities had begun distributing medical masks and respirators to those who need them.

The Yadrovo landfill was opened in 2008 and is a dumping site for garbage from Moscow and nearby regions. Local residents have been staging protests, demanding the closure of the landfill, for some time.

The Moscow regional authorities have said that the waste dump will suspend its operations until April 14, after which the old section of the dump will be closed.

On March 7, Volokolamsk authorities declared a temporary state of emergency, saying the level of hydrogen sulphide in the air was recorded as 2.5 times higher than normal and the level of nitric oxide was double usual levels because of a gas leak at the landfill.

With reporting by TASS