The Ukrainian and Russian authorities have publicly accused each other of spying.

乌克兰政府和俄罗斯政府相互公开指责对方从事间谍活动。

Ukraine said it had expelled开除，驱逐 four Russians and detained another on suspicion of espionage¹间谍活动.

Russia's FSB security service confirmed the incident but said its actions were a response to Ukrainian espionage.

Ukraine's relations with its former Soviet² master have been strained紧张的 in recent months but two weeks ago Russia returned an ambassador to Kiev基辅.

The row comes days before the second and decisive round of Ukraine's presidential election, in which relations with Russia are an issue.

Sensitive time

Ukraine said that the five alleged³ Russian spies were caught possessing a camera concealed隐藏的 inside a pen, other espionage equipment and $2,000 (£1,250) - a reported bribe⁵ for a Ukrainian contact.

The head of Ukraine's security service says that the five were trying to obtain military secrets.

The FSB said its actions were a response to the recruitment of Russians by the Ukrainian security services.

The accusations⁶控告，谴责 come at a highly sensitive time.

The mutual⁷ recriminations反责，揭丑 also come just two weeks after Russia returned an ambassador to Ukraine, ending a five-month diplomatic rift裂口，不和.

And on Sunday, Ukrainians will vote in an election to choose a successor to outgoing President Viktor Yushchenko.

Mr Yushchenko's time in office has been marked by strained relations with Moscow, and his departure was being seen as an opportunity for an improvement in ties between the two countries.