COPENHAGEN (Reuters) - Icelandic police have restricted access to a volcano that has been spewing out "life threatening toxic gas pollution" since it began erupting on Monday, the department of civil protection and emergency management said.

Residents of the Reykjanes peninsula, near the capital Reykjavik, have been encouraged to sleep with windows closed and to switch off ventilation, the department said in a statement on Facebook late on Monday.

"The police, after counsel from scientists, have decided to restrict access to the eruption site due to enormous and life threatening toxic gas pollution," the department said.

"For the next hours it is highly likely that gas will build up around the eruption site due to low wind. Those who have already undertaken the hike to the eruption site, or are already there, are strongly advised to leave the area," it said.

(Reporting by Louise Breusch Rasmussen, editing by Robert Birsel)