MOSCOW/KIEV (Reuters) - Flights between Russia and Ukraine will be terminated on Sunday after the countries exchanged sanctions against their airlines amid a standoff over Moscow's support of separatists in the east of Ukraine.

Kiev said last month it would ban direct flights by Russian airlines, including flagship carrier Aeroflot, from Oct 25 to punish them for flying to Crimea, a peninsula Moscow annexed from Ukraine in 2014.

It also banned Russian planes carrying military hardware or troops from flying over Ukrainian territory.

The Kremlin called the move "another act of madness" and swiftly responded by closing its airspace to Ukrainian airlines, also effective from Sunday, although both sides expressed willingness to talk about lifting the ban.

Ukrainian Infrastructure Minister Andriy Pyvovarsky said on Friday that consultations with Russian officials had been held in Brussels and would continue on Saturday.

Pyvovarsky estimated that air passenger traffic between the two countries stood at 657,000 in the first half of 2015 with Russian airlines handling two-thirds of that.

Ukraine has accused Russia of sending arms and troops to help pro-Moscow separatists fighting its soldiers in the east of the country, in a conflict which has killed nearly 8,000 people since April 2014. Russia denies involvement.