Gaidamak who last week bought a 55 percent stake in Betar did not reveal how much he spent to increase his holding to 100 percent when speaking at a news conference to make the announcement alongside Finance Minister Ehud Olmert.
Gaidamak was largely unknown to Israeli soccer fans before Sunday. He broke onto the Israeli sports scene last month when he took a controlling stake in Hapoel Jerusalem basketball club.
Abramovich has poured a fortune into Chelsea a move which paid off last season when they won the Premier League title for the first time in 50 years.
Gaidamak said he was surprised by the relatively small amount he needed to invest in Betar a distant fourth last season and felt confident his money could make a great difference to the faltering club.
'(My outlay) is some dozens of millions of shekels and I think that for this amount I can be very useful... I will meet those responsible for the team and the coach to see what they need from me' Gaidamak told Israel's Channel 5.
In reaching out to the Israel's Arab minority Gaidamak handed over a cheque for £200000 to Bnei Sakhnin as a one-off donation to help the poorest club in the Premier League make up a shortfall after they lost a major sponsor.
Play in the Israeli Premier League begins next weekend.
'We should create some kind of balance and if... they (Sakhnin) cannot get money from other sources we Israeli Jews should be there to help the development of Arab Israeli sport because they are citizens of Israel and they play in the same league' Gaidamak said.
Gaidamak denied to Channel 5 any involvement in an investigation in Israel into alleged money-laundering scams.
'l would like to say now in front of the camera... I was never interrogated by the police (in the money-laundering investigation)... Russian Jewish money is the most honest the most dynamic money in the world' he said.