ECOWAS says to send troops to Mali, Guinea-Bissau ABIDJAN (Reuters) - West African regional bloc ECOWAS said on Thursday it will send military forces to Mali and Guinea-Bissau to monitor their transitions back to civilian rule after their coups, and will impose sanctions if junta leaders try to cling to power. The regional body expects both countries to organize and hold presidential elections in 12 months, it said in a statement issued following the conclusion of a meeting of heads of state in Ivory Coast's economic capital Abidjan. Soldiers in Mali, once viewed as a poster-child of democracy in Africa, overthrew the government in March, while the army of tiny coastal nation Guinea-Bissau seized power and derailed elections during a putsch on April 12. "The heads of state and of government decided to take all the necessary measures in order to assist Mali in the re-establishment of its unity and of its territorial integrity," according to the ECOWAS statement, read to ECOWAS officials and journalists late on Thursday. "To this effect the heads of state and of government instructed the commission to begin with immediate effect the deployment of the standby force of ECOWAS conforming to the approved mandate," it said. It said it would also send a force to Guinea-Bissau, and threatened junta leaders in both countries with sanctions if they did not meet the conditions it set, including the release and security of ousted officials. The body, whose military and economic heavyweight is Nigeria, gave no details on the size of the deployments, but a Western diplomat told Reuters the contingent bound for Mali could number between 3,000 and 5,000. Mali's coup came amid a Tuareg rebellion in its vast desert north and opened the door for the rebels, strengthened by fighters and weapons from Libya's war, to seize control of the region in the days that followed. The junta which deposed president Amadou Toumani Toure weeks ahead of elections meant to replace him has since named a transitional government, marking one of the first steps toward the restoration of constitutional order. Toure fled the country for neighboring Senegal. In Guinea-Bissau, soldiers detained ex-prime minister Carlos Gomes Junior weeks ahead of a presidential election run-off he was expected to win against rival Kumba Yala. The country's shadowy self-styled Military Command announced last week plans to set up a transitional government charged with setting elections sometime in 2014, but the proposal was rejected by the United Nations, ECOWAS and the African Union. ECOWAS sources told Reuters on Wednesday the regional body planned to send a 638-strong regional force to Guinea Bissau within days to protect state institutions and people - and idea diplomats said risked triggering conflict. The former Portuguese colony has suffered several army uprisings since independence in 1974, but this latest has been a setback to Western efforts to combat drugs cartels using the country as a stopoff point to Europe. Reporting by Joe Bavier; Writing by Richard Valdmanis; Editing by Myra MacDonald