The Charter Hall Office REIT (real estate investment trust) has recorded an increase in its portfolio value of 1.7 per cent to about $3.5 billion as at 30 June 2011, compared to the valuation in December 2010.

External valuations were taken on 24 properties, which represented 76 per cent of the portfolio by value, while the remainder was valued  internally.

"We are pleased to see value uplift at Moonee Ponds, Victoria, and NCR House, North Sydney, reflecting the recent leasing achievements at these two assets," Charter Hall Office REIT chief executive Adrian Taylor said.

"In supporting our strategy of reweighting to Australia, we have continued to see an improvement in Australian asset values as leasing conditions improve and tenant demand increases."

United States office assets represented almost $1.6 billion of the total value.

"The improvement in the US portfolio valuations is a positive signal for the US sale process and we look forward to receiving phase two bids in the near term," Taylor said.

"We remain focused on having binding purchase and sale agreements for the US portfolio by the end of the September quarter."

But capital expenditure and movements in exchange rates weighed on the book value of the trust and this led to a decline in book value of 0.4 per cent from $3.510 billion at the end of 2010 to $3.496 billion at the end of June this year.

This had a negative effect of 2.9 cents on the net tangible asset per unit of the trust.