UK spy chiefs to appear in public together for first time to answer lawmakers' questions

The heads of Britain's intelligence agencies will for the first time give public — and televised — testimony to U.K. lawmakers, amid fierce debate over intelligence tactics following allegations of spying on other governments.

Andrew Parker and John Sawers — heads of Britain's domestic security agency MI5 and foreign spy service MI6 — will appear along with Iain Lobban, director of electronic surveillance agency GCHQ, to take questions from Parliament's Intelligence and Security Committee on Thursday.

The committee says the trio will be questioned on the work of their agencies, their current priorities and threats to the U.K., but not on ongoing operations.

The spy chiefs' appearance will be televised with a slight delay. The committee previously has taken testimony in private from the security chiefs.