* Deal biggest military purchase since Communism fall
* Ruling party defends contracts
* Parliament could overturn president's veto (Adds ruling party comment, president's quotes)
SOFIA, July 23 (Reuters) - Bulgarian President Rumen Radev on Tuesday vetoed a deal to buy eight new Lockheed Martin F-16 fighter jets, describing a lack of consensus over the purchase as "extremely worrying".
The $1.26 billion deal would be the country's biggest military purchase since the fall of Communism three decades ago.
But Radev, a former air force commander, said the sharp disputes in parliament during the debate on its ratification showed that public consensus on the contracts had been neither sought nor achieved.
"Because of the shortened legislative procedure, a number of important issues such as prices, warranties, delivery times, penalties, indemnities, and so on, have remained unclear," he said.
"The commitment of the Republic of Bulgaria to obligations, for years to come, without a national consensus and conviction in the mutually acceptable conditions of the treaty, is extremely worrying," Radev said in a statement.
In 2017, an interim government selected the Gripen built by Sweden's Saab but the deal was later cancelled and a new procedure was launched a year later.
Radev said it was important that Bulgaria receive "a full package of equipment, accompanying equipment and personnel training".
"The public needs a definite answer as to whether this is actually achieved by the contracts."
The ruling centre-right GERB party defended the contracts and expressed its readiness for another vote at a parliamentary session on Friday. Parliament could overrule Radev's veto with a vote of at least 121 votes in the 240-seat assembly.
"We have a consensus that we need to modernise (Bulgaria's) armed forces," Konstantin Popov, chair of parliamentary defence committee, said. "The F-16 is a wonderful airplane."
The Black Sea state, a staunch Washington ally, is looking to replace its ageing Soviet-made MiG-29 aircraft after 2023 and improve its compliance with NATO standards.
Reporting by Angel Krasimirov; editing by Jason Neely and Alison Williams