Unabated attacks by Boko Haram in Cameroon have sparked soaring food insecurity and driven 190,000 people from their homes, creating fertile ground for recruitment by the jihadists, the UN warned.

Nigeria-based Boko Haram fighters have in recent months carried out fewer spectacular attacks and suicide bombings in neighbouring Cameroon.

But the UN humanitarian coordinator for the country Najat Rochdi said the jihadists were attacking villages and burning homes and fields across northern Cameroon on a daily basis.

"The impact of the violence by Boko Haram is not over, and we have to remain vigilant," she told AFP this week.

While the current attacks are less eye-catching, they have a more devastating effect, Rochdi said.

She said that in the last six months alone, the number of Cameroonians displaced within their own country had jumped from 60,000 to 190,000.

In addition, Cameroon is hosting 60,000 refugees from Nigeria and another 312,000 from the Central African Republic, amounting to more than 500,000 displaced people in all.

The number at risk of going hungry, she said, has meanwhile soared from 900,000 to 2.4 million since January, as Boko Haram fighters have continued to attack fields and food supply routes.

"It is a kind of silent crisis, which is really the danger," Rochdi said, warning that if humanitarian needs are not addressed in Cameroon, "we will see a radicalisation" of young people in the country.

"If people are not left with some hope, the only alternative for them is Boko Haram," she cautioned.

She said the problem was communicating what truly is at stake to international donors, with only 30 percent of the requested $280 million (248-million-euro) humanitarian aid budget for Cameroon this year funded so far.

"The gap in terms of humanitarian assistance is just dramatic," she said, insisting that providing desperately need assistance in the country was not just about saving lives.

"It is also about making sure that there is no fertile ground for recruitment by Boko Haram."

Boko Haram's insurgency is one of the world's most brutal conflicts, leaving at least 20,000 people dead since it began in 2009, with more than 2.6 million others displaced.

A multinational force from Nigeria, Niger, Chad, Benin and Cameroon has since last year significantly weakened the group but have been unable to vanquish the Islamists entirely.

Rochdi acknowledged that Boko Haram had been more successful in recruiting inside Cameroon last year, but said that could quickly change.

Some 250 children recruited or abducted by Boko Haram have meanwhile managed to escape over the past nine months or so, she said, adding most of them were "in very bad shape".

"Some of them were little girls who came with their babies. They were raped every day," she said.