Mozambican police said members of one of its elite units were involved in the murder of a poll observer in a ruling party stronghold just ahead of next week's election.Anastacio Matavele, 58, the head of a local election observation mission, was shot dead Monday while driving away from a workshop in Xai-Xai, the capital of the southeastern Gaza province. National police commander Bernardino Rafael said there were five perpetrators involved in the "homicide", of whom "four (were) police officers of the Republic of Mozambique assigned to the Gaza rapid intervention sub-unit".He said the attackers suffered a fatal car accident as they fled the scene, colliding into another vehicle at full speed.Two died on the spot and two were seriously injured, while a fifth managed to escape.He added that two senior provincial police officers had also been suspended and that a commission of inquiry had "15 days to present a detailed report". Gaza is a stronghold of Mozambique's ruling Frelimo party, which has dominated power since the southern African country gained independence from Portugal in 1975.President Filipe Nyusi is widely expected to win re-election in next Tuesday's election. The opposition alleges that the government has already started tampering with the electoral process.Mozambique's poll observation mission has accused Frelimo supporters of attacking opposition members, blocking campaigns and burning their homes.The European Union (EU), the US embassy and local civil society groups have condemned Matavele's assassination."Yesterday's attack was also an act of disrespect against the Mozambican people and their legitimate right to participate in the democratic process," said an EU statement on Tuesday, which called "for a peaceful and orderly remainder of the electoral process".Mozambique is trying to recover from the legacy of decades of unrest after the completion of a historic treaty in August between the government and former rebel group Renamo, now the main opposition party.Nyusi is running against Renamo's Ossufo Momade and two other candidates.