Ofqual has said headteachers are "best placed to decide whether exams should go ahead as planned" in light of the terrorist attack in Manchester last night.
The exams regulator has issued advice to schools and said it will speak to exam boards about making provisions for pupils who may have been affected by the attack on a pop concert.
Twenty-two people, including children, have been killed and 59 injured in the bomb attack at a concert by singer Ariana Grande at Manchester Arena last night.
'Seek advice from schools'
In a statement to schools and pupils today, Ofqual said: "Many students and teachers are likely to have been affected by the tragic events in Manchester last night.
"Headteachers are best placed to decide whether exams should go ahead as planned."
Thousands of students across the country are sitting their GCSE exams this week.
The exams watchdog added: "We will consider with the exam boards how the provisions that are normally made for students who are unable to sit their exams when planned, or who take their exams but whose performance might be affected, will be applied.
"Students and their parents should seek advice and information from their schools. Our thoughts are with everyone affected."
A statement from the exam boards today has said no students will be "disadvantaged" if school leaders decide to postpone exams.
Released by the Joint Council for Qualifications (JCQ) it said: "Our thoughts go out to everyone affected by last night's terrible incident in Manchester.
"GCSE and A level examinations are taking place today across the UK but, understandably, some students, schools and colleges will have been affected by the bombing.
“School leaders are best placed to decide if exams should go ahead and, if they decide they are not, exam boards will make sure that no student is disadvantaged. This is known as Special Consideration and more information can be found here: A guide to the special consideration process 2016-17.
"Schools and colleges affected by the bombing should contact the relevant exam boards. Students affected should speak to their teachers."
Ofqual has also reissued guidance for schools today on what to do if exams are seriously disrupted.