With his deadly attacks targeting Norway's Labour Party, Anders Behring Breivik said he aimed to halt its recruitment, but instead the party has seen a flood of sympathy and growing support since the massacre.

A poll published Sunday by the Dagbladet daily showed support for Prime Minister Jens Stoltenberg's party had ballooned 11.1-percentage points from June to 41.7 percent.

"You don't have to be an election expert to see the sympathy effect," political scientist Frank Aarebrot told the paper.

"Voters who voted for Labour in the last elections but who were in doubt about whether they should vote have returned en masse to the Labour Party," he added.

Local elections are scheduled in Norway on September 12, while parliamentary elections will be held in 2013.

The party was the main target of Behring Breivik's rampage, as he first set off a powerful car bomb outside the Oslo offices of the centre-left government before opening fire at the party's youth summer camp on the Utoeya island near the capital.

Seventy-seven people were killed in the two attacks.

The Synovate poll of 500 people between July 29-30 dealt a blow to the 32-year-old rightwing extremist, who during his first appearance before a judge last Monday said he had wanted to "deal the Labour Party the biggest possible losses to strangle its recruitment".

In a 1,500-page manifesto sent out prior to the attacks, Behring Breivik, a radical Islamaphobe, held the party responsible for creating a multicultural society in Norway.

He has said he carried out the attacks on his own, something investigators say is appearing more and more credible, but he has also mentioned "two other cells in Norway" and a number of others abroad.

The populist right Progress Party, of which Behring Breivik had been a member until 2006, meanwhile lost three points, landing at 16.5-percent support in Sunday's poll.

Party leader Siv Jensen has tried to distance herself and her party from the killer.

"It makes me all the more sad to know that this person was one of us," she said last week.

The leader of France's far-right National Front (FN) party also hit back Sunday after mainstream parties denounced remarks by the party's founder, her father Jean-Marie Le Pen, on the Norway attacks.

Marine Le Pen, whose party has condemned the attacks as "cowardly and barbaric acts," said "several parties of the left and affiliated associations have, in a particularly shameful and cynical way" tried to take advantage of the situation.

In a statement on his website Friday, Jean-Marie Le Pen wrote that the Norwegian government's "naivety" in not correctly handling immigration was to blame for the recent mass killing there.

Prime Minister Stoltenberg, who has been widely hailed for his handling of the tragedy with his calls for tolerance, calming presence and support to victims and their families, has meanwhile seen his popularity skyrocket.

According to another poll published Wednesday, 94 percent of Norwegians are satisfied or very satisfied with the way he has reacted to events.

Deeply shaken by the worst attacks on Norwegian soil since World War II, the Scandinavian country was more than a week later still struggling to return to normal life.

The Norway Cup, one of the world's largest football gatherings, began in Oslo Sunday with a minute silence in honour of those killed.

Survivors of the July 22 attacks were among more than 30,000 girls and boys from around the globe who kicked off the annual event.

"This is a first step towards life as normal, one week on," organiser Terje Lund told AFP. "It is important to offer the children something else to think about, something else to do."

Behring Breivik is being held in isolation in a high-security prison, and two psychiatrists are set to begin assessing this week whether he is legally insane, as prosecutors seek to bring him to trial next year.

They are expected to report their findings by November 1.