By Angeliki Koutantou ATHENS (Reuters) - Greece wants its existing privatisation agency to handle current tenders because setting up a new one will take time, a senior privatisation official said on Wednesday. The issue -- described as minor by Finance Minister Euclid Tsakalotos on Tuesday - has held up final agreement on privatisation in talks with lenders this week. Under the deal, the country has pledged to wrap up a series of privatisations that were halted when the leftist government of Prime Minister Alexis Tsipras came to power in January.