Greece's economy will shrink by over 4.5 percent this year, the country's finance minister said on Friday, adding that a new bailout deal for the troubled euro zone member would not be completed before mid-October.

After Finland secured a collateral on loans to Greece, Austria, the Netherlands and Slovakia said they wanted the same, complicating efforts to finalize the rescue deal. The four account for about 11 percent of the euro zone contribution to the new 109 billion euro ($153.5 billion) Greek bailout.

Finance Minister Evangelos Venizelos said all bilateral decisions are up for approval by the other euro zone members and that it would be a while before the new bailout negotiations are completed.

We should not expect to be finished before the first or second week of October, because parliaments need to vote and banks to complete their own processes, he told SKAI Radio.

He did not say whether Greece was negotiating collateral with countries other than Finland. A government official said on Thursday Athens was not holding any such talks.

Venizelos painted a grim picture of the economy, saying the slump this year would be worse than expected, but said no new austerity measures were in the pipeline. Tough salary cuts and tax hikes have prompted street protests and pushed Greece into its deepest recession in about 40 years.

In previous months the (economic contraction) estimate was 3.8-3.9 percent. Now, the new range is over 4.5 percent, he said. If we try to apply the revenue and spending measures we voted in parliament, no new measures will be needed.

(Reporting by Dina Kyriakidou; Editing by Toby Chopra)