United Nations helicopters have fired on forces loyal to Ivory Coast president Laurent Gbagbo.
The s helicopters fired four missiles at a pro-Gbagbo military camp in Ivory Coast's main city of Abidjan, witnesses said.
"We saw two UNOCI (UN mission in Ivory Coast) MI-24 helicopters fire missiles on the Akouedo military camp. There was a massive explosion and we can still see the smoke," one of the witnesses said.
The camp is home to three battalions of the Ivorian army.
The attack came after special representative of the UN secretary general, Choi Young-jin, said the UN was planning a response to 'reckless and mindless' attacks on civilians and UN staff.
"We are planning action, we can no longer condone their [Mr Gbagbo's forces] reckless and mindless attack on civilians and the United Nations blue helmets with heavy weapons," Mr Young-Jin told the BBC.
Mr Young-jin accused the rebels of 'targeting' United Nations peacekeepers with snipers."We will be using our air assets," he told the BBC's Focus on Africa Programme
Earlier, France sent more troops to the country in a bid to protect civilians as forces backing presidential claimant Alassane Ouattara prepared a "lightning" assault to remove Laurent Gbagbo from power.
As hundreds of pro-Ouattara soldiers gathered on the outskirts of Abidjan, waiting to launch what they say will be the final assault to unseat Mr Gbagbo, explosions could be heard from the direction of the presidential palace.
Mr Gbagbo has refused to cede power after a disputed November 28th election which United Nations-certified results showed Mr Ouattara won, but Mr Gbagbo rejected the results and accused the UN of bias. The political standoff that followed has now turned into a resumption of the civil war of 2002-03.
After swiftly taking control of most of the country, pro-Ouattara forces have met fierce resistance in Abidjan where Mr Gbagbo's troops are holding on to positions around the presidential palace, Mr Gbagbo's residence, and state television.
Forces loyal to President-elect Alassane Ouattara have captured much of the city since the start of their attack last Thursday, while fighting continues around the presidential palace and at some army bases, residents said today.
Yesterday saw less intense fighting than the previous three days, with sporadic gunfire and explosions in several neighbourhoods. Nervous citizens ventured out to get food and water today after being holed up at home because of the fighting.
Speaking on the pro-Ouattara TCI television channel yesterday, Mr Ouattara's prime minister Guillaume Soro said their strategy had been to encircle the city, harass Mr Gbagbo's troops and gather intelligence on their arsenal.
"The situation is now ripe for a lightning offensive," which he said would come any time soon.
France said today it was sending an extra 150 soldiers from the West African nation of Gabon to help protect civilians in Ivory Coast.
The deployment brings the number of French troops in Ivory Coast to 1,650. France has about 12,000 nationals in Ivory Coast and the French military contingent has already mounted patrols in Abidjan and taken control of the airport.
It had been expected that Mr Ouattara's forces would quickly overrun Mr Gbagbo's troops following defection by high ranking officers, but they have manage to withstand the assault so far and regain control of the state broadcaster RTI.
Through the television channel, they have broadcast virulent anti-French and anti-UN messages, while rallying support from Mr Gbagbo's youth wing, the Young Patriots, who have formed a human chain around Mr Gbagbo's residence and presidential palace.
Mr Gbagbo's camp has also received a potential morale booster with the return of army chief general Philippe Mangou, who had sought refuge at the residence of the South African ambassador on Wednesday as pro-Ouattara troops advanced on Abidjan.
More than 1,500 people have been killed since the violence began five months ago.
The ICRC said it stuck by an estimate of 800 killed in the western town of Duekoue alone in intercommunal violence in one day last week, which Mr Ouattara's camp has said was "exaggerated".
"Two members of our staff went there and gathered consistent testimony. Our colleagues saw hundreds of bodies with their own eyes," said ICRC spokesman Steven Anderson.
African Union secretary general Jean Ping urged both sides to "show restraint and protect civilians."
He hoped for "a swift resolution of the crisis and for Mr Ouattara to take up the office to which he has been democratically elected".
Ivory Coast's $2.3 billion 2032 bond, on which it defaulted at the end of January, fell as much as 1.7 points today, reversing some of last week's gains as the market nervously eye the standoff which some fear may become prolonged.
Reuters