(Updates with new blast)

MAKHACHKALA, Russia, Oct 23 (Reuters) - A roadside bomb injured two people in Russia's troubled Dagestan region late on Tuesday, hours after one woman was killed and five passengers hurt in a blast in a minibus, local media reported.

Dagestan is part of a swathe of southern Russian, including neighbouring Chechnya, where Moscow's forces have been struggling to contain violence caused by a combination of an Islamist insurgency, organised crime and clan feuds.

Itar-Tass news agency said a taxi was caught in a powerful blast as it drove through Makhachkala, the capital of Dagestan.

The taxi driver was slightly hurt but his female passenger was in serious condition, the agency quoted police as saying. Police said they believed the blast was caused by a bomb concealed in a rubbish bin.

Earlier, an explosion tore through a minibus near the Dagestani town of Khasavyurt when it was about 100 metres (yards) from a police post.

Police initially said the woman victim was a suicide bomber, but an official later said it appeared she was carrying explosives which went off accidentally.

Three of the five wounded people were rushed to hospital with severe injuries, police said.

"We are investigating the possibility that it was a suicide-belt but that is not the main line of inquiry," said a local law enforcement official, who did not want to be identified.

The official said initial forensic examination suggested the woman had been carrying components for an explosive device, but not a ready-made bomb.

Itar-Tass quoted a local prosecutor as saying: "It seems most likely that the blast happened accidentally, so it would be extremely hard to say she was a suicide-bomber."

In neighbouring Chechnya, Russian forces have been fighting a long-running campaign against separatist insurgents.

Chechnya is now broadly calm, but the violence has spilled over into neighbours including Dagestan and Ingushetia. Bomb blasts and gunfights between police and insurgents are regular occurrences.

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