India has appealed to the International Court of Justice (ICJ) to order Pakistan to suspend the execution of a retired Indian naval officer convicted of espionage.
Deepak Mittal, joint secretary of India's Foreign Ministry, told the court in The Hague on May 15 that the death sentence handed down to Kulbhushan Jadhav's last month followed an "unjust" trial in a Pakistani military court.
He said that Pakistan failed to respond to Indian demands for information about the case.
Pakistani representatives were to address the tribunal later in the day.
Jadhav's arrest and trial has further strained tense relations between the nuclear-armed neighbors.
Pakistani officials say Jadhav was arrested in the southwestern province of Balochistan in 2016.
India denies Jadhav was a spy and claims he was kidnapped from Iran. It lodged a protest at the ICJ last week, accusing Islamabad of "egregious violations" of the Vienna Convention On Consular Relations.
With the case expected to take months or years to resolve, New Delhi is calling on the international court to order Islamabad to prevent Jadhav's execution pending the final outcome.
The court's president has already written to Pakistan urging it to refrain from steps that could affect the hearings, effectively a request to prevent the execution from taking place.