Ukrainian Foreign Minister Dmytro Kuleba said there had not been any recent diplomatic communications between Russia and Ukraine at the level of their foreign ministries and that the situation in the port of Mariupol, which he described as "dire", may be a "red line" in the path of negotiations.
"Mariupol may be a red line", he told CBS News in an interview on Sunday.
Ukrainian soldiers resisted a Russian ultimatum to lay down arms on Sunday in the pulverized port of Mariupol, which Moscow said its forces had almost completely seized in what would be its biggest prize of the nearly two-month war.
Ukrainian Prime Minister Denys Shmyhal said troops in Mariupol were still fighting despite a Russian demand to surrender by dawn.
"We didn't really have any contacts with Russian diplomats in recent weeks at the level of foreign ministries", Kuleba said in the interview.
"The only level of contact is the negotiating team that consists of the representatives of various institutions and members of parliament. They continue their consultations at the expert level but no high level talks are taking place," he added.
The foreign minister said he was expecting "intensification of heavy fighting in eastern Ukraine" in the coming weeks.
When asked about prospects of U.S. President Joe Biden visiting Ukraine, the foreign minister said Ukraine would be happy to welcome him and that a visit from him will send "an message of support."
The White House, however, said earlier this week there were no plans for Biden to visit the country that Russia invaded in late February.
"We are not sending the president to Ukraine," White House spokesperson Jen Psaki said on Friday.
(Reporting by Kanishka Singh in Washington; Editing by Toby Chopra and Grant McCool)
