Aug 21 (Reuters) - Fitch on Monday downgraded Swedish property company SBB's long-term issuer default rating (IDR) to "B-" from "BB+", citing insufficient progress on raising enough liquidity and unfavorable real estate and capital market conditions.

'B' ratings indicate that material default risk is present, but a limited margin of safety remains, Fitch says on its website regarding issuer default ratings.

Fitch also downgraded SBB's senior unsecured debt rating to 'B+' from 'BB+'and said that the ratings remain on rating watch negative.

"SBB continues to undertake asset disposals but execution risk remains high," the ratings agency said.

SBB, one of Sweden's largest commercial landlords and owner of many rent-regulated residential and community service properties, has been trying to repair its battered finances over the past few months, with its shares plunging over 90% on concerns over its financial position.

Last month, Fitch Ratings had placed the Swedish real estate group on rating watch negative. (Reporting by Kanjyik Ghosh in Bengaluru; Editing by Shweta Agarwal and Shailesh Kuber)