Liberian ex-president Charles Taylor is expected to address the international court that found him guilty of aiding and abetting war crimes.It is his last chance to speak at The Hague tribunal before he is sentenced later this month.The prosecution wants an 80-year prison term, which the defence says is excessive.Taylor was convicted of arming rebels in Sierra Leone during its civil war and helping to plan atrocities.In its landmark ruling last month, the Special Court for Sierra Leone found the 64-year-old guilty on 11 counts, relating to atrocities that included rape and murder.The BBC's world affairs correspondent Mark Doyle says Taylor may tread carefully in what he says, so as not to risk angering the judges.However, the defendant believes many Western and African leaders have conspired against him and our correspondent says those leaders will be watching his speech with trepidation.From the outset of the trial, Taylor has insisted he is innocent of all charges. 'Blood diamonds'Taylor will deliver his statement from a witness box, instead of from his usual chair at the back of the court.Prosecutors have said that Taylor's ill health and age, or the fact that he has a family, should have no impact on the sentence, or where he should serve it.In written filings, prosecutors said a sentence of 80 years would reflect the severity of the crimes and the central role that Taylor had in facilitating them."The purposely cruel and savage crimes committed included public executions and amputations of civilians, the display of decapitated heads at checkpoints... public rapes of women and girls, and people burned alive in their homes," wrote prosecutor Brenda Hollis.But defence lawyers said the recommended sentence was "manifestly disproportionate and excessive", and that Taylor had only been found guilty of an indirect role - aiding the rebels, rather than leading them.They said their client should not be made to shoulder the blame alone for what happened in Sierra Leone's war.The court should not support "attempts by the prosecution to provide the Sierra Leoneans with this external bogey man upon whom can be heaped the collective guilt of a nation for its predominantly self-inflicted wounds", his lawyers wrote.During the 1991-2002 Sierra Leone civil war, Taylor supported Revolutionary United Front rebels who killed tens of thousands of people.The war crimes included murder, rape, the use of child soldiers and the amputation of limbs. In return, Taylor received "blood diamonds".The sentence is due to be handed down on 30 May.Taylor is widely expected to appeal against any prison sentence and the hearing could continue for several more months.Under a special arrangement with the international court, any prison term Taylor does receive will be served in Britain.