Ukrainian President Volodymyr Zelensky invited his Russian counterpart Vladimir Putin to discuss the need to de-escalate tensions in Donbas immediately after four Ukrainian servicemen were killed in an attack near Shumy, Donetsk region, on March 26, Zelensky's press secretary Yulia Mendel said.

"The request for negotiations was submitted immediately after the death of four servicemen of the Ukrainian Armed Forces, back on March 26," Mendel told Interfax-Ukraine on Monday.