The French Ministry for Education cancelled a returns visit to Britain by 16 French exchange students follow in the recent IRA explosion London.
The French authorities withdrew permission for the trip shortly before the French students from College St Therese, Paris, set off for London to stay with pupils from the St Thomas More RC Comprehensive School in Eltham.
It is also understood the French authorities refused to provide insurance for the visit.
"Everyone is disappointed as a lot of work went into organising accommodation and activities for the French students. We believe that the students would have been perfectly safe and well looked after in our pupils' homes," said Sister Ann Maire of St Thomas More School.
A spokeswoman for the College St Theresa confirmed that the French Ministry for Education had cancelled the trip. She said this was because the education authorities believed the students would be at risk while travelling in London.