A Norwegian family was flabbergasted to find that what appeared to be a piece of a meteorite had crashed through the roof of their allotment garden hut in the middle of Oslo, media reported Monday.

The rock weighing 585 grammes (one pound, four ounces), which split in two, probably detached from a meteorite observed over Norway on March 1, experts said, and had landed on the empty hut in the Thomassen family's allotment in a working-class neighbourhood of the Norwegian capital.

Astrophysicist Knut Joergen Roed Oedegaard and his wife Anne Mette Sannes, a meteorite enthusiast, identified the object as a breccia, or a rock composed of broken fragments of minerals or rock.

"It is a sensation in more than one way. On one hand because it is rare that a piece of meteorite goes through a roof and on the other hand because it is a breccia, which is even harder to find," Sannes told AFP.

She said the owners of the meteorite pieces wanted to keep them in Norway, maybe in a museum.

Meteorites speed through space and generally break up as they enter our atmosphere, but it is extremely rare for the debris to fall on inhabited areas, according to Serge Koutchmy, a researcher at the Paris Astrophysical Institute.

"This family is very lucky," Koutchmy told AFP.

"First off because the piece of meteorite did not cause much damage, but also because it is worth a small fortune," he said.

A meteorite from Mars, for instance, can fetch around 5,000 kroner (670 euros, $876) per gramme, according to geophysicist Hans Amundsen quoted on the website of the Verdens Gang daily, adding though that it remained unclear where the meteorite pieces that landed in Oslo came from and how rare they were.