* West African leaders meet in Paris to define strategy
* Nigeria, Cameroon failing to coordinate regionally
* France fears Boko Haram spreading beyond borders (Adds Hollande)
By John Irish
PARIS, May 17 (Reuters) - Britain offered on Saturday to send advisers to help the Nigerian military organise its efforts to fight Boko Haram rebels, who have kidnapped more than 200 schoolgirls and threaten to destabilise the wider region.
British Foreign Minister William Hague, speaking before the start of a meeting of Western and African leaders in Paris, said the Nigerian military was not organised in a way to deal effectively with the Islamist group.
French President Francois Hollande told the meeting that Boko Haram was now a threat to all Western and Central Africa - a point that was supported by reports of a suspected Boko Haram attack on a Chinese work site in Cameroon on Friday might.
Although Boko Haram have been fighting for five years, carrying out many bombings and attacks on civilians as well as security forces, the kidnapping last month of more than 200 girls from a school in Chibok, northeast Nigeria, has focussed world attention on them.
Outrage over the mass abduction prompted Nigerian President Goodluck Jonathan - criticised at home for his government's slow response - to accept U.S., British and French intelligence help in the hunt for the girls.
France, itself a target of Islamist militants for its military intervention against rebels in Mali, brought together Nigeria's neighbours Chad, Cameroon, Niger and Benin, and Western officials for the Paris meeting to try to improve cooperation in the fight against the militants.
"Nigerian security forces have not been well structured for this kind of thing and that has been shown by the problem getting worse," Hague told reporters.
"We can help with that which is why we are offering to embed military advisers within the Nigerian headquarters."
But Nigeria must still lead the way, he said.
"Nigeria has the main responsibility and must be the leading nation in tackling this and that includes to mount an effective security response and improve development," he said.
The Nigerian military must uphold human rights as it goes about its task, the British minister added.
With about 6,000 French troops operating in either Mali to the northwest or the Central African Republic to the east, Paris has a big interest in preventing a deterioration in Nigeria's security.
It fears Boko Haram could spread north into the Sahel and beyond Cameroon into the Central African Republic.
"Boko Haram is a major threat for all of western Africa and now central Africa with proven links to AQIM (al Qaeda in the Islamic Maghreb) and other terrorist organisations," Hollande said.
French diplomats have ruled out any Western military operation but said they expected a regional plan to take shape for countering Boko Haram.
"A comprehensive plan needs to be put in place from exchanging information to coordinating action and controlling borders," Hollande said.
The night before Hollande spoke, suspected Boko Haram rebels attacked a Chinese work site in northern Cameroon on Friday and at least 10 people are believed to have been kidnapped, the regional governor said.
The group has killed more than 3,000 people in its war to establish an Islamic state in mostly Muslim northeast Nigeria.
Nigeria has complained the far north of Cameroon is being used by Boko Haram militants to shelter from a Nigerian military offensive and to transport weapons, and has urged Cameroon to tighten border security.
"The first focus is about the girls, but that requires these countries work together particularly Cameroon and Nigeria who have not enjoyed strong, positive relations in recent years," Hague said. (Reporting By John Irish, Editing by Angus MacSwan)