MADRID, July 19 (Reuters) - Spanish telecom operator Telefonica said on Saturday it would cut its debt by 200 million euros ($169 million) after selling a controlling stake in its optic fibre network in Colombia to buyout fund KKR . The Spanish company plans to spin off the unit and keep a 40% stake, while a local unit of KKR would take the rest. The operation values the fibre network in Colombia at $500 million. KKR intends to expand the coverage to 4.3 million households in the country by 2024 from 1.2 million at the moment, the buyout fund said in a statement. The transaction still requires regulatory approvals, both companies said. The sale is part of a wider Telefonica plan to reduce its debt by selling assets.