The Hague - France accused Equatorial Guinea on Monday of wanting to "paralyse" French criminal procedure in a top-level corruption probe, as it urged judges to throw out a case against it before the UN's top court.
Malabo has dragged Paris before the International Court of Justice in a bitter diplomatic row, accusing it of violating the diplomatic immunity of its vice president Teodorin Obiang.
Son of Teodoro Obiang, long-time leader of the oil-rich central African country, Teodorin Obiang has been prosecuted by a French court on charges of embezzling $180m of public funds to finance his jet-set lifestyle.
France's representatives however hit back as a hearing opened before the Hague-based ICJ, with delegation member Alain Pellet saying Equatorial Guinea attempted to "slow down, or even paralyse the criminal procedure launched in France." Malabo's decision to take the matter to the ICJ is an attempt "to give their case more prominence" argued Pellet, who said Paris challenged the ICJ's jurisdiction.
"France has not accepted the jurisdiction of this court under any title whatsoever to entertain those facts on which Equatorial Guinea seeks the court to rule," French representative Francois Alabrune added.
Obiang, 48, was tried in absentia and sentenced in October to a three-year suspended sentence for corruption.
The top official from the small central African state was also given a suspended fine of $35m for money laundering, corruption and abuse. His lawyer has said he will appeal.
But Equatorial Guinea has also lodged a complaint with the ICJ in The Hague, the UN's top court set up to resolve disputes between countries.
Four days of hearings opened on Monday, with France setting out its reasons why it believed the ICJ is not competent to hear the case.
Paris has challenged the ICJ's jurisdiction in the case since it first opened, citing the UN's Convention against Transnational Organised Crime.
"Equatorial Guinea's request is unreasonable because it lacks any legal basis," Alabrune said.
Equatorial Guinea contends however that not only was the Vienna Convention conferring diplomatic immunity on Obiang broken, but French officials also failed to uphold the diplomatic status of a building it maintains is Malabo's embassy in Paris.
Teodoro Obiang Nguema is Africa longest-serving president and has ruled the country with an iron fist since 1979. He extended his rule in April 2016 when he was re-elected with 93.7% of the vote.
He appointed his son as vice president in June 2016 - two years after the first charges were first brought in France.
In 2012, French authorities swooped on the Obiang family's six-storey mansion on the Avenue Foch - one of the most upmarket addresses in Paris - seizing it along with a fleet of luxury cars including two Bugatti Veyrons and a Rolls-Royce Phantom.
Police also took away vanloads of valuables, including paintings, a $4.2m clock and fine wines worth thousands of euros per bottle.
The UN judges in The Hague in 2016 urged France to ensure the protection of the diplomatic mission in Paris, but sidestepped Malabo's request to order Obiang's trial to be halted.
Relations between the two countries have furthered deteriorated after Malabo's foreign minister, Agapito Mba Mokuy, said an attempted coup in December had been hatched on French soil, although he said the French authorities had "nothing to do with" it.