* Issue expected to launch Tuesday - source
* Coupon seen around 4.75 percent - source
ROME Jan 14 (Reuters) - Italy will attempt to sell 15-year debt this week for the first time in more than two years, taking advantage of a sharp rally in bonds of euro zone states hit hardest by the sovereign debt crisis.
The Italian treasury said on Monday it had mandated five banks to sell a new BTP bond maturing on Sept. 1, 2028, to be launched in the near future depending on market conditions.
The five banks are Banca IMI SpA, Barclays Bank PLC, Credit Agricole 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 in September 2010, before the country was engulfed by the sovereign debt crisis that pushed its benchmark 10-year borrowing costs above 7 percent at their peak in November 2011.
"I expect the bond to be launched tomorrow (Tuesday). I don't expect the size to be below 3 billion euros, probably in the 3-5 billion euro range," a source close to the deal said on Monday.
The source said the coupon would be around 4.75 percent.
"There has been strong interest in the issuance, including from asset managers," the source said.
According to Alessandro Giansanti, strategist at ING, the sale will be finalised by Tuesday before German and Spanish auctions due later in the week.
"The right time is now, since there is a lot of liquidity on the market," Giansanti said, adding the new bond could carry a coupon of 4.75 percent, up from the 4.50 percent offered by the current benchmark maturing March 1, 2026.
After the treasury statement on the new issue, the yield on Italian 10-year bonds rose to around 4.19 percent, up 7 basis points from Friday levels.
Analysts told Reuters on Friday they were expecting the treasury to issue a new 15-year benchmark bond in the following days to take advantage of the rally in periphery bonds at the beginning of 2013.
At a mid-December sale, Italy sold 730 million euros of its March 2026 BTP bond, paying a yield of 4.75 percent.
The yield on this paper hovered around 4.47 percent on Monday after the treasury announcement.