French authorities have urged pregnant women and children under seven living in the vicinity of the Notre-Dame Cathedral in Paris to undertake blood tests over fears of lead contamination following the tragic fire that engulfed the 800-year-old monument last April.

The move was described "as a precaution" after Ile de France's Regional Agency of Health (ARS) announced that it had learned that a child had been found to have levels of lead "higher than normal standards."

It also added that an investigation has been launched into the affected child's situation, saying it would also probe if other reasons could have caused a spike in the child's lead levels.

Some 300 tonnes of lead from the cathedral's roof and steeple had melted in the blaze, risking contamination to surrounding areas, according to the French environmental campaign group, Robin des Bois.