NEW YORK - SL Green Realty Corp, a New York office owner and commercial real estate lender, said on Tuesday it expected to play a role in the restructuring of the debt on two huge Manhattan apartment complexes teetering on the edge of default.

We will actively monitor the situation very closely and the potential exists to be a part of some form of restructuring or resolution of this investment, Marc Holliday, SL Green chief executive, said in a conference call with analysts, following the company's release of its third-quarter financial results.

Last week, New York State's highest court found that Tishman Speyer and BlackRock Realty Advisors, which bought the sprawling Stuyvesant Town and Peter Cooper Village complex for $5.4 billion in 2006, and original owner MetLife illegally converted rent-stabilized apartments into substantially more expensive market-rent units.

BlackRock Realty is an arm of money manager BlackRock Inc.

Even before the court's ruling Rob Speyer, president of Tishman Speyer, said the joint venture that bought the neighboring properties would have to restructure the debt.

The complex includes 56 apartment buildings, housing about 25,000 residents on 80 acres near Manhattan's East River.

The project is now living off its dwindling interest reserves which are expected to run out by the end of the year or shortly after that.

SL Green and its offshoot Gramercy Capital Corp invested $200 million in the most junior part of the $1.4 billion mezzanine debt. GIC contributed $575 million and Hartford Financial Services Group Inc (HIG.N) invested $100 million. Deutsche Genossenschafts-Hypothekenbank AG also had $100 million in mezzanine debt.

Some $3 billion of mortgage debt, comprised of 10-year interest-only loans due in 2016, are securitized in commercial mortgage-backed securities (CMBS) in five deals. (Reporting by Ilaina Jonas; Editing by Tim Dobbyn)