Abu Dhabi on Thursday called on Doha to stop "supporting terrorist groups and individuals" and strongly denied human rights abuses against Qatari citizens before the UN's top court.
The bitter Gulf crisis pitting Doha against its neighbours including the United Arab Emirates, Saudi Arabia and Bahrain moved to the international courts Wednesday, with Qatar accusing the UAE of fostering an "environment of hate" against its citizens.
But Abu Dhabi's representatives Thursday fired back, saying relations were cut with Qatar "because of its support for terrorism, its interference with the affairs of its neighbours and its dissemination of hate speech."
"Our government has asked Qatar time-and-again to cease this conduct," the UAE's ambassador to the Netherlands, Saeed Alnowais, told the International Court of Justice.
"Although Qatar repeatedly committed to do so, it has failed to live up to its commitments," Alnowais said at the Hague-based ICJ.
At the start of the crisis last June, Qatar, a gas-rich peninsula nation, found its only land border closed, its state-owned airline barred from using its neighbours' airspace, and Qatari residents expelled from the boycotting countries.
Doha earlier this month dragged the emirates before the Hague-based body -- which rules in disputes between countries -- accusing it of racism and human rights abuses against its citizens.
The legal moves at the ICJ come after Saudi Arabia, the UAE, Bahrain and Egypt severed all ties with Doha on June 5 last year accusing it of supporting terrorism and Iran.
Doha denies the allegations and its lawyers Wednesday told a 16-judge bench that Abu Dhabi has implemented a "series of broad discriminatory measures" against Qataris including expelling them, stopping their access to health care and criminalising any statements that express sympathy with Qatar.
Basing its claim on the 1965 International Convention on the Elimination of All Forms of Racial Discrimination (CERD), Qatar also accuses the UAE of shutting down its media networks including Al Jazeera.
Both Doha and Abu Dhabi are signatories to the convention.
Doha is demanding the ICJ urgently intervene and hand down provisional measures to stop further prejudice as well as, over the longer term, order "full reparation, including compensation for the harm suffered as a result of the UAE's actions in violation of the CERD."
UAE representative Alnowais however said his country "completely rejects the allegations, all of which are without any merit or basis."
"Qatar has put forward no credible evidence to substantiate any of these claims," he said, adding it consisted "only of anecdotal and unverified statements," he said.
"The UAE's measures against the Qatari government are carefully measured to have the least possible impact on ordinary people," Alnowais added.
Diplomatic efforts to resolve the crisis have so far proved fruitless in what was previously one of the most stable regions in the Arab world.
The wrangling has shattered old alliances and rendered the six-nation Gulf Cooperation Council practically obsolete, pushing Qatar towards Turkey and Iran.
Qatar maintains the dispute is an attack on its sovereignty and punishment for pursuing an independent foreign policy.
Experts say it could now take the ICJ's judges weeks or even months to hand down a decision.
Meanwhile in a surprise tit-for-tat move, Saudi Arabia, the UAE announced in state media Wednesday they too planned to file their own case at the UN's top court against Doha, accusing it of violating their airspace.
The UAE has filed two complaints with the ICAO over what Qatar's rivals say are airspace violations that threaten civil aviation.
Doha's neighbours say the ball is in Qatar's court to end the crisis. It has been handed a list of 13 demands by its Gulf neighbours, including closing Al Jazeera, removing Turkish troops from the country and scaling back its cooperation with Iran, with which it shares the world's largest gas field. It has not met any of them.