* Invel Real Estate to buy about 66 pct of NBG's Pangaia property unit

* Deal to be partly financed by NBG

* NBG to retain management for 5 years

By George Georgiopoulos

ATHENS, Nov 17 (Reuters) - National Bank of Greece, the country's largest lender, is close to clinching a deal to sell a majority stake in its fully-owned real estate arm Pangaia to private equity firm Invel Real Estate, two bankers close to the deal told Reuters on Sunday.

The sale is part of restructuring efforts by National Bank (NBG) aimed at boosting its capital base.

Greece's top four banks are implementing restructuring plans agreed with the European Commission as part of conditions imposed for their bailouts. The plans involve job cuts, branch closures and asset sales.

"The agreement will close in the next 10 days. Invel will acquire about 66 percent of Pangaia for more than 600 million euros ($808 million)," one of the bankers said.

Invel will pay part of the purchase price for Pangaia in cash, contribute equity in the form of real estate and finance the rest with a loan from National Bank, the bankers said.

Dutch-based Invel was set up in March 2013 to take advantage of opportunities in the European real estate market by offering investors the ability to co-invest in deals.

BSG Real Estate, controlled by Israeli businessman Beny Steinmetz, will be one of the co-investors in the transaction, the bankers said.

"NBG will retain management control at Pangaia for five years," the other banker said. "The loan by NBG for part of the majority stake will be at a spread of 275 basis points, secured by real estate contributed by Invel."

The bankers said the sale would strengthen National Bank's Core Tier 1 capital adequacy ratio by 40 basis points to 9.6 percent. The Bank of Greece plans to conduct stress tests later this year.

Pangaia's real estate portfolio includes office buildings, branches operated by NBG and other property recently acquired from the country's privatisation agency.

Pangaia may pursue a listing on the Athens stock exchange by 2015, one of the bankers said.

The agreement has been approved by the Hellenic Financial Stability Fund (HFSF), the bank rescue vehicle that recapitalised the country's big four banks in the summer and is now their major shareholder, one of the bankers said.

Last month, Canadian firm Fairfax Financial Holdings announced its intention to raise its stake in Greek real estate firm Eurobank Properties.