The Union of South American Nations (Unasur) will act as an international observer to monitor Venezuela's presidential election in October, according to an agreement inked here on Wednesday.

The accord signed by Tibisay Lucena, head of Venezuela's National Electoral Council (CNE) and Unasur rotating President Rafael Roncagliolo, who is also Peru's foreign minister, marks the first time Unasur serves as an observer in a presidential poll since its establishment in 2008.

"The process of Latin America's elections has progressed technically and professionally, and is now known for being efficient, impartial and transparent," said Rocangliolo.

"But the democratic process is still facing challenges in satisfying increasing social demands and extending the benefits to all citizens."

Unasur's observer mission will include a leader and a coordinator, as well as four observers from each country of its 12 members. The head of the mission will submit a report to the CNE after election results are announced.

Some 18.9 million eligible voters are expected to vote in the October 7 race between incumbent President Hugo Chavez, who is running for a third term, and opposition candidate Henrique Capriles.

Earlier this month, electoral officials launched a trial run with a small number of voting booths, and a nationwide trial run is scheduled for August 26.

The pre-election exercises are designed to test the voting system, which is to be fully automated, and familiarize voters with the process, said CNE officials.