The UAE has rejected a request by Egypt to free 11 of its citizens held on suspicion of training Islamists in how to overthrow governments, local newspapers reported on Saturday.
Egypt's Muslim Brotherhood last week said some of the detainees were its members and demanded they be freed, saying they had been wrongfully arrested.
The UAE has long voiced distrust of the Muslim Brotherhood that helped propel Egyptian President Mohamed Mursi to power last year after the overthrow of veteran ruler Hosni Mubarak.
Egypt sent a presidential aide and its intelligence chief, General Mohamed Shehata, to the UAE for talks following the arrests.
"They (UAE officials) explained that a suspect cannot be released before the case goes to court," the English-language Gulf News reported, adding the Egyptian delegation was told the UAE had a 'strong court system and justice will take its course'.
The Arabic-language al-Khaleej said the 11 suspects were under investigation by state security prosecutors over "serious charges".
The oil-producing UAE arrested about 60 Islamists last year, accusing them of plotting to undermine governments in the Gulf region.
Al-Khaleej, citing an unnamed source, last week said there were close ties between Egypt's Muslim Brotherhood and leaders of the UAE Islamists in detention. It said the detained Egyptians had given "a number of courses and lectures ... on elections and ways to change systems of government in Arab countries".
Mahmoud Ghozlan, a Brotherhood spokesman in Cairo, rejected the charge that the 11 were seeking to destabilise the UAE.
The son of one of those arrested said his father, Ali Sonbol, was a doctor and not involved in political activities.
Relations between Egypt and the UAE soured after Mubarak - a longtime Gulf ally - was toppled in 2011.
Last month, UAE Foreign Minister Sheikh Abdullah bin Zayed al-Nahayan summoned Egypt's ambassador over claims carried by Egyptian media that the UAE was behind a plot against Egypt's leadership, saying they were "fabricated".
The Brotherhood has sought to reassure Gulf states that it has no plan to push for political change beyond Egypt's borders.
Thanks to their state-sponsored cradle-to-grave welfare systems, the UAE and other Gulf Arab monarchies have largely avoided the unrest that has unseated long-serving Arab rulers elsewhere in the past two years.