By Olena Harmash and Ivana Sekularac

BELGRADE/KYIV, Aug 8 (Reuters) - Belgrade will support Ukraine's independence and aims to improve economic cooperation between the two countries, President Aleksandar Vucic said ‌on Saturday, but he stopped short of any pledge to impose sanctions on Serbia's long-time ‌ally Russia.

Ukraine's President Volodymyr Zelenskiy is on a two-day visit to Belgrade ending on Saturday. It is his first since ​he became president in 2019, although his wife Olena visited Belgrade in 2024.

Vucic, a populist who faces early elections in the coming months, is striving to maintain a delicate balance between the Serbia's aspiration to join the European Union and historic and economic ties with Russia.

Belgrade condemned Russia's military invasion of Ukraine in 2022, ‌but has refused to impose sanctions ⁠on Russia. Serbia also remains dependent on Russia for most of its gas.

Vucic, who has met Zelenskiy several times, most recently in Kyiv on July 15, ⁠said Serbia will maintain support for Ukraine's territorial integrity, including territories seized by Russia since 2014.

For its part, Ukraine has refused to recognise the 2008 independence of Kosovo, which Belgrade considers as part of Serbia.

"You have ​never heard ​a single bad word about our country, neither ​from Volodymyr Zelenskiy nor anyone else (in Ukraine), ‌and I am extremely grateful to our Ukrainian friends for that," Vucic said.

Vucic said he was sceptical that either Serbia or Ukraine would achieve rapid accession to the European Union, but that Belgrade would support Kyiv's bid to join the bloc.

Both Vucic and Zelenskiy said the two countries want to improve economic cooperation and complete a free trade agreement by the end of the year. The deal is ‌crucial for Serbia's bid to join the World Trade ​Organisation, and a prerequisite for its EU membership. Ukraine has ​been blocking it since 2005 over quotas ​and tariffs for its agricultural sector.

Zelenskiy said he and Vucic discussed joint infrastructure ‌projects and cooperation on energy and food security ​for the upcoming winter ​in Ukraine, heavily hit by Russian attacks on energy facilities.

"We are developing all formats of cooperation which can give our people ... more resilience," Zelenskiy said.

The Kremlin has accused Belgrade several times ​of selling ammunition to Ukraine ‌via intermediaries. Belgrade has denied it supplied ammunition to Ukraine but has said it ​has sold to other buyers worldwide. Vucic said he and Zelenskiy did not discuss military ​cooperation.

(Writing by Aleksandar Vasovic; Editing by Barbara Lewis)