By Helen Fawkes
BBC News, Kiev
A series of raids have been carried out on opposition buildings in Ukraine with just over a week to go before presidential elections are held.
Opponents say the raids are an attempt to destabilise the situation
The election campaign has become increasingly tense, with the opposition accusing the authorities of violence.
The government warned opponents it will use force if civil unrest breaks out.
The vote is a contest between two men. The pro-western opposition leader, and the prime minister, who has the backing of the outgoing president.
Ukraine's security service, as well as the police, carried out the searches.
Offices and homes of members of the opposition were raided in Kiev and at least four other cities.
One of the organisations targeted was Pora, a student group which is already the subject of an investigation into allegations of terrorism.
Last week, police said they discovered explosives at the group's office. Pora has denied the charge.
The president's spokesman said the searches were done to restore order.
As the operation was carried out, the Ukrainian opposition leader claimed in an interview on national TV that the authorities were plotting acts of terrorism.
Viktor Yushchenko, who is also a presidential candidate, alleged the searches were part of a general plan to destabilise the situation in the run-up to the election.
Members of the opposition are planning a mass protest on polling day, 31 October, if the result is seen as fraudulent.
On Thursday, the Mayor of Kiev warned the opposition that if there is a major disruption in the capital he will declare a state of emergency.