UPDATE 3-Italy to sell new 15-year BTP, first since Sept 2010

* Issue expected to launch Tuesday - source * Coupon seen around 4.75 percent - source ROME, Jan 14 (Reuters) - Italy will attempt to sell 15-yeardebt this week for the first time in more than two years, takingadvantage of a sharp rally in bonds of euro zone states hithardest by the sovereign debt crisis. The Italian treasury said on Monday it had mandated fivebanks to sell a new BTP bond maturing on Sept. 1, 2028, to belaunched in the near future depending on market conditions. The five banks are Banca IMI SpA, Barclays Bank PLC, CreditAgricole Corp, Goldman Sachs and JP Morgan Securities PLC. Books for the bond are likely to open on Tuesday. The last time Italy sold a new 15-year benchmark was inSeptember 2010, before the country was engulfed by the sovereigndebt crisis that pushed its benchmark 10-year borrowing costsabove 7 percent at their peak in November 2011. "I expect the bond to be launched tomorrow (Tuesday). Idon't expect the size to be below 3 billion euros, probably inthe 3-5 billion euro range," a source close to the deal said onMonday. The source said the coupon would be around 4.75 percent. "There has been strong interest in the issuance, includingfrom asset managers," the source said. According to Alessandro Giansanti, strategist at ING, thesale will be finalised by Tuesday before German and Spanishauctions due later in the week. "The right time is now, since there is a lot of liquidity onthe market," Giansanti said, adding the new bond could carry acoupon of 4.75 percent, up from the 4.50 percent offered by thecurrent benchmark maturing March 1, 2026. After the treasury statement on the new issue, the yield onItalian 10-year bonds rose to around 4.19 percent, up 7 basispoints from Friday levels. Analysts told Reuters on Friday they were expecting thetreasury to issue a new 15-year benchmark bond in the followingdays to take advantage of the rally in periphery bonds at thebeginning of 2013. At a mid-December sale, Italy sold 730 million euros of itsMarch 2026 BTP bond, paying a yield of 4.75 percent. The yield on this paper hovered around 4.47 percent onMonday after the treasury announcement.