The shooting took place in the agricultural state of Barinas, about 450 kilometers (280 miles) from the capital Caracas, when supporters of Chavez and Capriles traveling in motorcades began an argument on a local road.

Capriles' party, Primero Justicia, said gunmen then fired from a van, which they said may have belonged to a state oil company.

The interior minister in the Chavez cabinet, Tareck El Aissami, said police were investigating what he called an "isolated" incident.

Both on campaign trail

At the time, Capriles, who has lobbied for a more business-friendly social welfare state and an end to Venezuela's high homicide rate, was campaigning in western Venezuela's Falcon state.  The 40-year-old state governor has accused Chavez of squandering oil revenues on foreign allies.

Chavez, 58, who has promised to "deepen" socialism if he wins a new six-year term, spent Saturday inaugurating public transport systems in Caracas, including a cable car in a large slum. He has accused Capriles of representing a right-wing elite.

Pollsters see tight race

Venezuela's presidential contest on October 7 looks set to be the tightest in the 14 years since Chavez came to power. He recently declared himself cured of cancer.

A majority of Venezuela's six best-known survey institutes put Chavez ahead by up to 10 percent. Two pollsters, however, put Capriles slightly out front, a gain his campaign has achieved in just months.

Satellite launch

In a new twist to Venezuela's recent modernization drive, China said on Saturday that it had successfully launched a Venezuelan earth-observation satellite from the Gobi desert.

Under Chavez, Venezuela has forged closer economic ties with China in recent years to reduce Latin American dependence on the United States. Last week, Caracas and Beijing signed an agreement to expand a joint gold mine in southern Venezuela.

China has made sizeable loans to Venezuela in recent years. In exchange, it purchases some 640,000 barrels of oil a day from Venezuela.

ipj/tj (AFP, AP, Reuters)