A teacher accused of stealing GCSE exam papers from a school in south London has resigned from her post.

The school at the centre of the scandal has been identified as the Archbishop Lanfranc secondary school in Croydon.

In a statement, headteacher David Clark said the woman - a teacher at the school for 13 years who has not been named - had resigned her position and left with immediate effect.

The teacher was arrested on Monday along with a man thought to be her husband and both have been released on bail.

The arrests followed a police raid in south-west London on a private tutorial college with which the couple had connections.

The raid followed a tip-off that pupils at the tutorial college were being coached using the GCSE maths paper they were due to take the next day.

Archbishop Lanfranc school says the teacher had responsibility for organising some language exams taken by external candidates, so had limited access to exam papers kept locked in a secure place.

It says no other exam papers are missing and it is reviewing procedures to ensure it cannot happen again.

But the exam board, Edexcel, has questioned the school's security and says that it will be "putting in special ongoing monitoring procedures to ensure that future breaches do not occur".

Police - acting on information from the exam board Edexcel - went to the tutorial centre at 1930 BST on Monday.

A spokesperson for the Metropolitan Police said they had arrested a man and a woman, both in their forties.

Students 'unaware'

Edexcel said in a statement that the students involved would not be disadvantaged.

"Their papers will be marked by a senior examiner and compared with their past performance," it said.

There will also be no impact on the hundreds of thousands of other students who sat the maths exam.

Edexcel says it makes daily random checks on schools to ensure that all scripts remained sealed until the day of the examination.

Other cases

"Visiting inspectors call in unannounced at any time during the examination period and have the right to see the sealed scripts," it said.

Mr Kerr condemned any attempts to cheat the examination system, which he said depended on trust.

Edexcel reports incidents to the Qualifications and Curriculum Authority (QCA), the exams regulator.

"The board is currently investigating other cases," it added - which a spokesperson said was quite normal during the "exam season".