A 16-year-old boy has died in Bahrain on the second anniversary of an uprising against the rule of the Sunni al-Khalifa family, the day after the government met with opposition groups to try and negotiate an end to the unrest.

The government says it has launched an investigation into the death, and has said the causes are still unknown.

“The case has been referred to the Public Prosecution and a thorough investigation is being conducted into the incident,” said a statement issued by the Information Affairs Authority. Opposition groups say the boy was killed at a demonstration in the village of Al-Daih after being hit with shotgun pellets fired by riot police.

The death will raise already heightened tensions as demonstrations were planned to mark the uprising that began on 14 February 2011. A significant police presence had been deployed in expectation of unrest. Major-General Tariq al-Hassan, chief of public security, urged people to remain calm on the anniversary and “resist the lure of troublemakers”.

On 13 February, several government ministers met with opposition figures and members of parliament in order to try and get a new political dialogue under way that would stop the unrest, which has continued since early 2011. Talks are set to continue later in February, but there are concerns that if there is further violence to mark the anniversary of the protest movement, it could sour relations between the government and the opposition.

King Hamad bin Isa al-Khalifa had commissioned an independent report into human rights abuses during a crackdown on protests in mid-2011. Although the findings of that report were welcomed by both sides, opposition groups say the government has failed to fully implement its recommendations.

Shia opposition groups want the recommendations from the latest round of talks to be put to a national referendum.