Georgia's opposition accused the government Friday of trying to keep it off the airwaves after police impounded 300,000 satellite dishes intended to boost an opposition tycoon's TV station.

The authorities however said the case was purely criminal and promised new legislation to ensure that opposition channels are broadcast freely throughout the ex-Soviet state for the first time during parliamentary polls in autumn.

Billionaire tycoon Bidzina Ivanishvili's opposition coalition said the government was trying to keep national television free of dissent ahead of the vote by impounding dishes during police raids in Tbilisi and several provincial towns on Thursday.

"The aim of the authorities is to maintain the information vacuum which has been made possible through government control of the federal TV companies," the Georgian Dream coalition said in a statement.

Ivanishvili has had repeated run-ins with the authorities since announcing his bid to oust President Mikheil Saakashvili's governing party in the elections, and has been fined tens of millions of dollars so far this year.

A company co-owned by the tycoon's brother was giving away the dishes for free to boost the client base of Ivanishvili's opposition TV station, which the authorities see as an election bribe.

"The whole thing has nothing to do with the freedom of speech and media," parliament chairman David Bakradze told AFP.

He said the law would be changed to give opposition channels unprecedented guaranteed airtime during election periods.

"We will introduce legislation which will guarantee that all TV channels can broadcast throughout the country during an electoral campaign, in order to make sure that alternative information is available for everyone," he said.

Georgian opposition channels have long complained of being denied a chance to broadcast nationwide, with the airwaves filled by allegedly pro-government stations.

During Thursday's raids, police sealed premises storing the satellite dishes, the property of the Global TV cable and satellite company that is co-owned by Ivanishvili's brother.

Georgia's prosecutor said an investigation was launched as the dishes could be considered electoral bribes.

"The measures were aimed at preventing a crime and also at protecting electoral processes from possible criminal intervention and ensuring citizens' and political parties' electoral rights and freedom of expression," the prosecutor's office said in a statement.

Georgia's interior ministry said it would maintain a "zero tolerance" approach towards election law violations.

"It is very regretful that Bidzina Ivanishvili and Georgian Dream seem to think they are above the law and are constantly and purposefully trying to weaken the law and, consequently, democracy in this country," Deputy Interior Minister Eka Zguladze told journalists.

Ivanishvili was fined more than $90 million (72 million euros) this month for breaking political funding laws in a series of violations including the distribution of the dishes, although the penalty was later cut to $45 million (36 million euros).

The formerly reclusive businessman, whose fortune is estimated at $6.4 billion, has revitalised Georgia's opposition with his bid to oust Saakashvili, although opinion polls suggest his alliance trails the governing party.