Iceland's spectacular, two-week old volcanic eruption entered a new phase Monday as television pictures showed a fresh fissure had opened up and begun spitting out lava.
The 200-metre (yards) long fissure, is a kilometre from the first eruption, which sits in the Geldingadalur valley, said an Icelandic Meteorological Office (IMO) statement.
It opened up around midday local time (1200 GMT), the IMO added.
Live television footage on state broadcaster RUV showed small amounts of smoking orange magma on the ground. The new stream of lava is running down into another valley, called Merardalir.
Images released by Iceland's Civil Protection office showed a long, thin stream of magma flowing down through the hills for hundreds of metres from the new fissure, the whole scene shrouded in fumes.
The Meteorological Office said helicopters were making sure people had evacuated the site and that scientists were on their way to evaluate the crack.
The authorities have sealed off access to the volcano site as a precaution and begun evacuating sightseers, said the IMO. People have been flocking there to see the spectacle since the eruption began on March 19.
Icelandic experts, who initially thought the eruption near Mount Fagradalsfjall would be a short-lived affair, now think it could last several weeks or more. The volcano lies just 40 kilometres (25 miles) from the capital Reykjavik.
While Iceland has more active volcanoes than any other country in Europe, the Reykjanes peninsula has not experienced an eruption since the 13th century -- although that one lasted about 30 years, from 1210 to 1240.
At the last count by Iceland's tourism board, 36,293 people had by Sunday visited the site, where lava has been pouring from two small craters, covering almost 30 hectares (74 acres).