The move is part of an updated business plan it will submit to the country's central bank later this year, NBG said on Tuesday.
The lender has almost full control of Finansbank, which contributed more than half of the group's 809 million euro ($1.1 billion) net profit last year.
NBG last week became the fourth major Greek bank to successfully tap international markets, with a 2.5 billion euro equity offering intended to plug a capital shortfall.
In a prospectus for its recently completed share offering, NBG said Finansbank operated 674 branches in Turkey in 2013 and would open another 25 by the end of this year.
NBG also confirmed it would take additional action to boost its capital by 1.040 billion euros.
Half of this sum will come from the completed sale of a majority stake in an upmarket Athens hotel, Astir Palace Vouliagmeni and the savings arising from a voluntary redundancy scheme, it said.
NBG will cover the rest by divesting non-core assets and shrinking its high-risk loan portfolio.