Pupils at two primary schools have been kept indoors at lunch-time after a fox was spotted in the playground.
The animal was spotted outside Cefn Onn Primary School, which shares a site with Ysgol Y Wern Primary School in Llanishen, Cardiff.
It followed an incident where twin babies in east London needed hospital treatment after being mauled by a rogue fox in their home.
Cardiff council said the children were kept in as a precaution.
The fox was first spotted on Monday when teachers at both schools were instructed to keep the children away from the playground at lunch-time.
The fox was spotted again before school began on Tuesday and the council sent its pest control team in to investigate.
A council spokeswoman said: "A fox was sighted in the school grounds earlier this week. The children were kept inside the school building as a precautionary measure.
"The schools acted in a routine way and in much the same way as they would have done had a dangerous dog been loose on the premises."
She said pest control officers had searched for a possible den for the fox and located signs of one underneath a temporary classroom on the site.
She added: "Investigations are ongoing but there is the possibility that the fox has left after being disturbed."
Neither school would comment directly on the incident.
There have been concerns about the potential risk foxes pose after nine-month-old twins Lola and Isabella Koupparis were attacked while sleeping in their cots at their home in Hackney on Saturday, 5 June.
Police said the fox apparently entered the house through an open ground-floor door before attacking the babies in an upstairs room.
Lola suffered injuries to her face and arm and Isabella was also bitten on the arm.
The twins' mother Pauline Koupparis told the BBC that she went to check on them after hearing a "funny cry".
She described the "living nightmare" when she switched on the lights to see the girls covered in blood and the fox still there.
Their four-year-old brother, who was also sleeping upstairs, was not hurt.
After the attack London mayor Boris Johnson said councils needed to "get together" and look at how they tackled pests.