Officers were understood to be treating the incident as a hoax. 

The exact nature of the threat was not known, but school officials told parents in an email seen by The Local that a menacing phone call had been picked up by the school's answering machine and appeared to have come from California in the United States.

The school stated that it had been advised by police not to evacuate the buildings.

Located in the suburb of Djursholm, the British International School of Stockholm provides education for up to 500 children, aged 3-13 (extending to 3-16 by 2017), of more than 45 nationalities.

The latest alert followed another bomb threat that sparked the evacuation of the school last week, as expat education centres in Stavanger in Norway and Budapest in Hungary received similar threats.

The British International School of Stavanger also experienced a second bomb alert shortly after the school day began on Tuesday, but pupils were allowed to return back to lessons after police found no evidence of any explosives.

Both fresh incidents came less than 24 hours after a number of Swedish schools and universities – including the University of Örebro in central Sweden – stayed closed for the day after they received various death threats via popular teens' app Jodel.