UPDATE 1-Norway 2010 oil/gas investments seen falling-lobby

* 2010 investments seen at 118 bln crowns vs 129 bln in 2009

* SSB estimates: 145 bln crowns in 2010 vs 143 bln in 2009

* Lower prices, postponed investments to explain drop

(Adds details, comments)

OSLO, Nov 12 (Reuters) - Investment spending by Norway's oil and gas industry should fall to some 118 billion Norwegian crowns ($21.11 billion) next year, down from a record 129 billion crowns in 2009, a lobby group estimated on Thursday.

In September, Statistics Norway (SSB) estimated investments on the Norwegian Continental Shelf (NCS) to rise to 145.4 billion crowns in 2010, slightly up from its 2009 estimate of 143.5 billion crowns -- and up from 123.9 billion in 2008.

"The estimate entails a still high activity level on the NCS over the next years, but at the same time it is expected a drop from 2009," The Norwegian Oil Industry Association (OLF) said in a report made by consulting firm Econ Poyry.

It said the biggest uncertainty was whether planned projects would be executed or postponed.

OLF said the reason behind the gap between its own estimates and those of SSB could probably be explained by its lower price increase estimate than what oil groups have reported to SSB and postponement of investments compared to those from SSB.

OLF said investment was expected to drop in 2010 and in 2011, but pick up after that. It estimated investments around 105 billion crowns in 2011.

SSB will present a new forecast on Dec. 3. (Reporting by Joergen Frich. Writing by Aasa Christine Stoltz)