A prominent London university has apologized for asking two students to cover up T-shirts depicting Muhammad and Jesus.

The representatives of the Atheist, Secularist and Humanist Society student union were wearing the shirts at a London School of Economics fair in October when they were told that displaying an image of Muhammad could constitute religious harassment and were asked to cover them up. Islamic law generally opposes any depiction of Prophet Muhammad.

Chris Moos and Abhishek Phadnis filed formal complaints.

LSE said Friday it has apologized to the students and acknowledged that, "with hindsight," wearing the shirts did not constitute harassment or violate the law or university policies.

The school said it takes free speech "very seriously" and will learn from the incident.