A journalist for the Russian channel TVTs, who had filmed a report about Ukrainian authorities' plans to separate the national Orthodox Church from the Moscow Patriarchate, was stopped at Kiev's Borispol airport late on Thursday and held overnight.
"This shocking incident makes Ukraine look not like a country seeking to position itself as a showcase for promoting democracy from West to East, but like a nation frightened by the truth coming from Russia, and restricting the press, which is absolutely impossible in a democratic state," Luzhkov told reporters.
The outspoken mayor, 71, has made a series of anti-Ukraine statements since being blacklisted by Kiev in May for suggesting Ukraine's Black Sea city of Sevastopol should be handed over to Russia. Earlier this month he said the treaty on friendship and cooperation between Russia and Ukraine should not be extended when it expires this year.
The detention of the Russian TV reporter, who had five video tapes confiscated, also met with strong criticism from Russia's Foreign Ministry.
Luzhkov said that Ukraine is wrong to link TVTs's coverage with the Moscow authorities.
"This is a Moscow government channel, but it is absolutely free," he said.
Luzhkov has courted controversy in Russia and abroad in the past, over the banning of what he calls "satanic" gay parades in the capital, and over accusations of using his power to secure lucrative construction contracts for his wife Yelena Baturina's company, and to influence Moscow court rulings.
Earlier this week British media reported that Luzhkov's wife, Russia's richest woman, had bought the second largest private house in London after Buckingham Palace for $100 million.