A suicide bomber has killed himself and four police officers in Chechnya. Another has been seriously injured.The attack took place in the village of Mesker Yurt, 20 kilometres from the capital Grozny. Just hours before the Russian Prime minister Valdimir Putin had been in the region on a secret, and surprise visit. It was in response to a wave of murders and attacks on security forces in recent months. The visit was a show of support for the Chechen leader Ramzan Kadyrov, a former rebel himself, and who took over the southern Russian republic when his father was murdered. Critics say he has brought stability to the former warzone at the price of basic freedoms, using strongarm tactics, or worse to supress dissent.