Mahdi Lournia was arrested, along with Makhsud-Jan, who is believed to be from Tajikistan, on Sunday by Dubai police as suspects in the March 28 assassination of Yamadayev. Dubai's police chief Lt. Gen. Dahi Khalfan Tamim said that several other suspects would be put on Interpol's wanted list.
President Kadyrov said on the presidential website that Lournia, an Iranian national, worked as a groom and that at the time of the assassination the employee, "was at the racetrack and in constant phone contact," adding that his racehorse had taken 5th place in the race. "After Lournia's arrest, my valuable horse is without a groom," he said.
Tamim also accused Adam Delimkhanov, a Russian State Duma deputy since 2007, of being a key suspect behind the killing. Delimkhanov served as Chechnya's deputy premier in 2006-07 and is reported to be a close friend of Kadyrov.
"Delimkhanov is the man behind the operation," Tamim told reporters.
The allegations provoked outrage in Russia's Chechen republic with Kadyrov saying "The allegation by the Dubai police chief concerning Adam Delimkhanov's involvement in the assassination of Sulim Yamadayev is untrue and is of an obviously provocative nature primarily aimed at tarnishing the Russian Federation and the leadership of the Chechen Republic."
Delimkhanov, who is currently on a visit to Syria, has called the accusations provocative and said he is willing to cooperate with the Dubai police in the investigation.
The Chechen parliament also issued an angry statement earlier on Monday denouncing "the ungrounded accusations against a person known for his solid public position."
Yamadayev, 35, a Hero of Russia who commanded the elite Vostok battalion in Chechnya, was shot by a lone gunman in the underground parking lot of the Dubai apartment building where he lived.
Yamadayev was officially dismissed as Vostok commander last August over alleged involvement in the 1998 abduction and murder of a Chechen businessman. The battalion, which answered directly to the federal Defense Ministry rather than Chechen authorities, has since been disbanded.
The killing of Yamadayev is the sixth in a series of killings of Chechens in the past year.
Sulim's brother, Ruslan Yamadayev, a former member of the Russian parliament's lower house, was gunned down in central Moscow last September. He was a prominent opponent of Chechen President Ramzan Kadyrov, who has denied any involvement in the either of the Yamadayev killings.