THE HAGUE - Defence lawyers for fallen Ivorian leader Laurent Gbagbo on Monday accused his bitter rival President Alassane Ouattara of seizing power by force aided by former colonial ruler France after disputed 2010 elections.

In an opening statement on the third day of Gbagbo's landmark trial on charges of crimes against humanity, defence lawyer Emmanuel Altit sought to unmask what he called a deliberate "smear campaign" against his client.

"Ouattara and his supporters wanted to seize power by force and the battle of Abidjan was, simply put, the very implementation of this strategy," defence lawyer Emmanuel Altit told the International Criminal Court (ICC).

Gbagbo and his co-accused Charles Ble Goude, a firebrand militia leader, have denied four charges of crimes against humanity after 3,000 people were killed following a disputed Ivory Coast vote.

Their highly-anticipated trial opened on Thursday at the court based in The Hague and is set to last three to four years.

Gbagbo declared himself the winner of the vote in late 2010, but major powers including France and the United States, as well as the United Nations, backed Ouattara, who had snatched a narrow victory.

The row triggered a bitter standoff that saw Gbagbo holed up in the fortified presidential palace and Abidjan - the country's main city and commercial capital - turned into a war zone. "France did not want peace to be negotiated," Altit said.

Then French president Nicolas Sarkozy "had shown unwavering support for his friend Ouattara," defence lawyer Jennifer Naouri told the court.

Gbagbo became the first ex-head of state to go on trial at the ICC and Chief Prosecutor Fatou Bensouda painted a vivid picture of the turmoil saying "the Ivory Coast descended into chaos and was the theatre of unspeakable violence."

She alleged on Thursday that Gbagbo, aided by the military, police and a youth militia group organised by Ble Goude, had clung to power by "all means necessary".

But Altit countered Monday that there had been a deliberate campaign to make Gbagbo "out to be some of kind demon" and "paint Ouattara as the good guy." "This is nothing more than a political narrative that has been heated up and re-served."

Gbagbo lawyer Agathe Bahi Baroan added that Gbagbo was "not a despot." "All his life he fought to defend democracy in the Ivory Coast," she said.

"Perhaps someone wants us to forget" alleged abuses committed by pro-Ouattara forces, Altit said, adding that even before the elections Ouattara had been recruiting mercenaries in neighbouring Burkina Faso, where preparations for the assault on Abidjan were made.

"The plans for military action had been drawn up by the plotters and schemers ... in cooperation with French military leaders during the entire crisis," he said.

"A fleet of French military aircraft delivered heavy weapons to pro-Ouattara combatants in the north of Cote d'Ivoire in February and March 2011, once again breaking the UN embargo," he said, using Ivory Coast's French name.

If the two men are convicted, the maximum penalty is usually up to 30 years in prison. Judges can impose a life sentence "when justified by the extreme gravity of the crime", according to the court's guiding statute.

Prosecutors are focusing on four specific incidents in the orgy of violence in the world's top cocoa producer, once held up as a beacon of democracy in a troubled continent.

One incident is the shelling of a market in the northern Abobo suburb on March 17, 2011 when pro-Gbagbo forces are alleged to have killed 40 people and injured 60 others.

Altit recalled how the incident had been loudly condemned at the United Nations.

But it led to a "ground offensive which had been prepared well in advance, craftily, sneakily, by French forces," he said.

And he regretted that no French witnesses had been called by the prosecution, saying only they "have the information needed to get" to the truth of what happened.

The ICC is accused by some African leaders of unfairly targeting them.

On Sunday, during an African Union summit, several continental heads of state backed a Kenyan proposal to pull out of the ICC on the ground that it is biased.