Up to 25 people have been killed after forces loyal to Laurent Gbagbo attacked a densely populated Abidjan suburb in the Ivory Coast
A UN Mission Spokesman said Gbagbo's security forces fired six projectiles and have killed between 25 to 30 people, up to 60 people were wounded.
Security in the main commercial city has been rapidly deteriorating since gunmen claiming allegiance to Ouattara took over its northern suburb, prompting pro-Gbagbo forces and allied youth militias to set up roadblocks and kill suspected rebels.
The United Nations said the confirmed death toll from Ivory Coast's violence since a disputed mid-December election is now 410.
The world's top cocoa grower has been in turmoil since the presidential election between Alassane Ouattara and Laurent Gbagbo.
Mr Ouattara is recognised internationally to have won the election, but Mr Gbagbo, the incumbent, has refused to concede.
'I went to the market where the rocket landed. There were 12 dead bodies there, and there are many wounded,' said witness Sumeiro Vassiriki.
Arouna Sylla, another resident, said at least 10 people had been killed and many wounded.
It was not clear who had fired the round in the area of the city which supports Alassane Ouattara.
Witnesses in Siaka Kone market in Marley, part of Abobo district, thought the shell had been fired by forces loyal to Mr Gbagbo, but there was no immediate comment from his camp.
His forces have had little access to the neighbourhood since it was taken over by Ouattara rebels.
The EU's emergency aid commissioner has urged the world not to overlook the humanitarian crisis in Ivory Coast which she says 'actually exceeds' that in Libya and had put the nation 'on the brink of civil war.'
She cited the latest UN estimates of almost 400,000 people on the move, 200,000 displaced from Abidjan alone, and 80,000 having already crossed into Liberia and Guinea.