Reykjavik's global Keflavik airport was not closed following the eruption, but each airline had to decide if it wanted to fly or not, IMO said.
This image taken by the Icelandic Coast Guard shows the lava flowing from the erupting Fagradalsfjall volcano near the Icelandic capital Reykjavik, on March 20, 2021. "The eruption is considered small at this stage and the eruptive fissure is app. 500 m long".
Iceland's Meteorological Office said on Saturday morning: "Lava fountains are small and lava flows are now a very local hazard".
The area began rumbling with increased seismic activity 15 months ago, and the tremors increased dramatically last month.
"There is no indication of production of ash and tephra, and there is no imminent hazard for aviation", the Met Office said on its website.
Police ordered residents living east of the volcano to close their windows and stay indoors due to the risk of possible gas pollution carried by the wind.
The Krysuvik volcanic system has been inactive for nearly 900 years, according to the Meteorological Office.
The eruption, known as an 'effusive eruption, ' is when lava steadily flows out of volcanic fissures.
Seismic activity had however slowed in the past few days.
Iceland has 32 volcanic systems now considered active, the highest number in Europe.
Iceland, located above a volcanic hotspot in the North Atlantic, averages one eruption every four to five years.
Unlike the eruption in 2010 of the Eyjafjallajökull volcano, which halted approximately 900,000 flights and forced hundreds of Icelanders from their homes, this eruption is not expected to spew much ash or smoke into the atmosphere, the IMO said.