Protesters gather in Ferguson ahead of the Darren Wilson verdict (Getty)
Protesters gather in Ferguson ahead of the Darren Wilson verdict Getty

Tensions are running high in Ferguson, Missouri, with police braced for riots ahead of the announcement on whether Darren Wilson, the police officer who killed an unarmed black teenager Michael Brown, will be charged.

Police today refused to rule out the use of rubber bullets, tear gas or armoured vehicles in response to protests, after groups demonstrating the killing of Michael Brown presented a 19 requests regarding "rules of engagement" to police, aimed at avoiding the violent clashes seen in August, reports the Guardian.

"If protesters are not violent, police will not be aggressive," Francis Slay, the mayor of St Louis, said at a press conference in Clayton. "But if some protesters turn violent or threatening, police will respond to keep everyone safe."

Police were accused of exacerbating the unrest in Ferguson after Brown was shot dead by adopting a confrontational approach, with officers using armoured vehicles and riot squads to contain demonstrators, and tear gas to disperse them.

The announcement of the verdict is expected any day now, with most protesters expecting legal authorities not to prosecute Wilson.

The prosecutor's office in St Louis County announced that it was planning a press conference where the decision would be announced, but did not provide details of when.

US Attorney General Eric Holder has appealed for Ferguson police to exercise restraint if protest become violent.

One local school has announced its plans to close for the beginning of next week, fearing that children could get caught up in violence, reports the Independent.

Earlier, police indicated that businesses would be given private 48-hour notice of the time the announcement would be made, to ready themselves for the expected backlash.

Among those appealing for calm was Michael Brown's father, Michael Brown Sr, who in a video posted online said "hurting others or destroying property it not the answer".

Wilson claims Brown attacked him, and he was forced to kill the 18-year-old to defend himself.

Witnesses claim that Brown was surrendering and has his hands raised when he was shot, with demonstrators adopting the gesture as the symbol of their protest.