Hundreds of medical students at King’s College Medical School have been forced to re-sit an exam after it featured questions available on a smartphone revision app designed by an honorary lecturer at the college.

King’s College has confirmed 420 students will re-sit an exam paper on 8 July, after the problem was discovered when students took the test on Monday.

It has deemed the exam compromised because some of its questions were available on a revision app developed by Rajesh Varma, a consultant obstetrician and gynaecologist at Guys and St Thomas’ Foundation Trust.

Dr Varma has an honorary senior lectureship at King’s, but does not have a teaching contract with the college. The university has launched an investigation and stopped Dr Varma from having involvement in the medical school programme while the probe takes place.

A spokeswoman for Kings College London said: “We are taking this matter extremely seriously and launched an investigation as soon as we were made aware of the issue. This is currently underway.”

She added: “We were made aware that some questions made available in an app were used in the paper. Because there were questions in common between the app and the paper, the paper was deemed compromised.

“The exam has already been re-scheduled for 8 July and students have been informed.

“We’re continuing to support the students and our investigation is underway.”