Cameroon's 85-year-old President Paul Biya on Tuesday vowed to pursue policies of decentralisation to address "frustrations and aspirations" in English-speaking regions hit by separatist unrest as he was sworn in for a seventh term in office.But he firmly ruled out secession for the troubled regions and accused armed radicals of plotting to impose "terror and desolation."On the eve of his inauguration, 79 school students were abducted in Bamenda, capital of the Northwest Region, in the worst incident so far in 13 months of pro-independence violence."I have carefully examined the frustrations and aspirations of the great majority of our fellow citizens" in the Northwest and Southwest Regions, Biya said in his inauguration speech."A good number of responses" will be provided "through the framework of accelerating the decentralisation process which is underway," he said.But he dismissed any prospect of secession, declaring "the future of our compatriots in the Northwest and Southwest lies in the framework of our Republic."In a rhetorical blast, he condemned "the yoke of extremism which imposes terror and desolation" and called on armed radicals to "lay down their arms and return to the right path.""The vast majority of (Cameroonians in anglophone regions) want the swift restoration of peace, within the national community," Biya said, urging them not to "lose hope".Biya, who has ruled the country for 35 years, was declared victor in the October 7 vote with 71% of the ballot.But the elections were marked by low turnout, violence and allegations of fraud.Cameroon's 22 million people are mainly French-speakers, but around a fifth are English-speaking.In 2016, resentment at perceived discrimination in education, the judiciary and the economy fanned demands for autonomy in the Northwest and neighbouring Southwest Region.In 2017, as Biya refused any concessions, radicals declared an independent state - the "Republic of Ambazonia" - and took up arms.Separatists have gunned down troops and police, boycotted and torched schools and attacked other symbols of the Cameroonian state, while the authorities have responded with a brutal crackdown.At least 400 civilians have died this year as well as more than 175 members of the security forces, according to an NGO toll.More than 300 000 people have fled the violence, many living hand-to-mouth in the forests, and some across the border into Nigeria. In the October election, turnout was a mere five percent in the Northwest and 15% in the Southwest, although Biya won more than two-thirds of the votes cast in both regions.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.