The Prime Minister has given his reaction to the murder of Northern Ireland prison officer David Black:
First and foremost this is a dreadful tragedy for the family and friends of David Black who has been so brutally murdered as he went about his work keeping the people of Northern Ireland safe. My heart goes out to them.
The Government I lead will do whatever we can to help the PSNI bring the perpetrators to justice.
These killers will not succeed in denying the people of Northern Ireland the peaceful, shared future they so desperately want.