PRETORIA, South Africa -- A South African court has ruled that a decision to drop 738 corruption charges against President Jacob Zuma should be reviewed, adding to the leader's legal troubles.

Judge Aubrey Ledwaba's ruling Friday allows prosecutors to re-open charges against Zuma which are linked to a multi-billion dollar arms deal in 1999.

Zuma has denied the corruption allegations, which were dropped in 2009 shortly before the election in which he became president.

Zuma is already under pressure over the decision by the constitutional Court, South Africa's highest court, that the president failed to uphold the constitution by not repaying an estimated $23 million in state funds used to improve his private residence.

Ledwaba, who was part of a full bench of three judges to rule on the matter, said the country's former chief prosecutor Mokotedi Mpshe was "irrational" when he dropped the charges of corruption, fraud and racketeering in 2009.

"This court finds that the decision of 1st April 2009 to discontinue the prosecution of the case against Mr Zuma is irrational and should be reviewed and set aside," Ledwaba said.

The charges relate to a case in which Zuma's former financial adviser Schabir Shaik was found guilty of fraud and corruption in June 2005.

The current case was brought by the opposition party, the Democratic Alliance, whose leader, Mmusi Maimane, grinned and punched the air as the judge read the decision.

"We have always maintained that the decision to drop charges against President Jacob Zuma was irrational," Maimane said after the ruling.