UPDATE 1-Development Securities posts flat H1 loss

* Maintains interim div at 2.4p/shr

* Says net asset value falls 11.2 pct

* Says to exercise caution in selecting investments

* Lower dev profits, fin costs, low int. income hurt co (Adds details)

Aug 24 (Reuters) - British property firm Development Securities Plc (DSC.L) on Monday reported a flat first-half pretax loss reflecting the further decline in property markets from 2008, and said it would continue to exercise caution in selecting further investments.

The company also maintained its interim dividend of 2.4 pence per share.

The loss reflected lower profits from development projects, a revaluation deficit of 12.2 million pounds ($20.2 million) related to investment property portfolio, net finance costs of 3.6 million pounds and negligible interest income, it said.

Development Securities' net asset value fell 11.2 percent to 143 million pounds, or 352 pence per share, from 161 million pounds, or 397 pence per share from Dec. 31 last.

"The property investment market has seemingly polarised between prime and near prime properties on one hand and secondary properties on the other," Chairman David Jenkins said in a statement.

Development Securities, which specialises in office and retail development projects, reported a pretax loss of 19.1 million pounds for the six months ended June 30. ($1=.6052 Pound) (Reporting by Kumar Alagappan in Bangalore; Editing by Gopakumar Warrier)