UPDATE 1-StealthGas to buy oil tankers, product carrier

(Recasts; adds details, share movement)

Sept 11 (Reuters) - Greek shipping firm StealthGas Inc (GASS.O) said it ordered two new Suezmax crude oil tankers, with an option of ordering two additional such vessels, and added it will buy a product carrier from an unaffiliated entity.

Assuming the option on the two additional vessels is exercised, the aggregate cost of the five vessels is about $403 million, the company said in a statement.

StealthGas also said it would sell Gas Amazon, a LPG carrier, for $11 million to an unaffiliated entity.

The two Suezmax crude oil tankers will be delivered in 2011, while the product carrier is set to be delivered in 2009.

If the company exercises its option related to the two additional vessels, they will be delivered in the first and second quarters of 2012.

StealthGas shares were down almost 6 percent at $14.76 in morning trade on Nasdaq. (Reporting by Antonita Madonna Devotta in Bangalore; Editing by Himani Sarkar)