CARACAS (Reuters) - Venezuela's political opposition said on Wednesday it had collected the required number of valid signatures to begin a recall referendum against President Nicolas Maduro, amid the country's economic crisis.

The painstaking process of validating the signatures began earlier this week. The electoral council has required that those who signed for a recall vote against the 53-year-old president return to polling stations to verify their signatures through fingerprint detection.

"We've achieved the goal," said Carlos Ocariz, the opposition governor of a Caracas district. "We have more than 236,000 valid signatures."

The electoral council had rejected more than a quarter of the nearly 2 million signatures collected by the opposition. It requires 200,000 signatures to begin the process. Once validated, the opposition must obtain 3.9 million signatures in just three days.

If the electoral council considers the signatures valid, it must call a referendum within 90 days. In order to push Maduro out, more than 7.5 million must vote against him - the number that voted for him in 2013, after the death of his predecessor Hugo Chavez.

Critics say the government is stalling the process at the behest of Maduro himself, who has said that the referendum will not take place this year.

The timing is important because if Maduro loses a referendum this year, the electoral council would call a new election which polls indicate he would likely lose. Losing a referendum after January, however, would mean Maduro would be replaced by his vice president, effectively leaving the Socialist Party in power.

The OPEC country is undergoing a severe economic and social crisis. Food riots and lootings are taking place daily amid shortages of basic foods and triple-digit inflation.

Maduro has struggled to maintain popularity amid the trouble caused by tight currency and price controls as well as Venezuela's heavy dependence on oil.

The government blames the problems on an "economic war" waged by the opposition with a helping hand from Washington.

(Reporting by Diego Ore; Writing by Girish Gupta; Editing by Sandra Maler)