BANGKOK, June 30 (Reuters) - Thailand and Myanmar finalised terms of a 4.5 billion baht ($133 million) loan to kick-start long-delayed development of Myanmar's Dawei Special Economic Zone, Thailand's transport minister said on Friday.

The two countries signed an agreement in 2008 to build the zone in Myanmar's southeast. But the multi-billion dollar project has been mired in difficulties, including widespread local opposition and problems mobilizing funding for its construction.

Thai Transport Minister Arkhom Termpittayapaisith met with Myanmar's Commerce Minister Than Myint on Friday to finalize conditions of the loan, which will have an interest rate of 0.1 percent, with a 10-year grace period and a 30-year repayment timeframe.

Italian-Thai Development Pcl (ITD) signed a deal in 2010 to build a deep-sea port and Special Economic Zone in Dawei. But it failed to secure first-phase financing.

The port, if completed, is expected to open a new gateway to the Strait of Malacca, one of the world's busiest shipping lanes, from Myanmar.

"Prior to this, ITD was not able to start construction because we could not agree on who will build the road", said Arkhom.

"But Myanmar government investment in the road will boost confidence for private investors".

Last year, Japan signed on as a third partner along with Myanmar and Thailand, a move some hoped would boost investor confidence in the long-delayed project.

According to Thailand's government, Myanmar is now responsible for the construction of a 138-kilometer (86-mile) road from Dawei to the Thai-Myanmar border, while ITD will develop a small port, a power plant, a reservoir and an industrial estate. ($1 = 33.9400 baht) (Reporting by Panu Wongcha-um; Editing by Amy Sawitta Lefevre and John Stonestreet