SINGAPORE'S state-owned investment companies have not been spared the fallout from the global market downturn.

The net portfolio value of Temasek Holdings fell 31 per cent between March 31 and Nov 30 last year, from $185 billion to $127 billion, Senior Minister of State for Finance Lim Hwee Hua revealed in Parliament on Tuesday.

The Government of Singapore Investment Corporation (GIC) also posted a decline in the value of its investments, but Mrs Lim did not reveal the numbers.

She said, however, that both Temasek and GIC have not done as badly as other market indices.

Temasek's 31 per cent drop in portfolio value was less than the 44 per cent plunge in the MSCI Singapore Index and the 45 per cent decline in the MSCI Asia ex-Japan Index in the same period, Mrs Lim said.

As for GIC, its investments have 'fallen by much less than the decline in global equity markets indices of 42 per cent for 2008'.

Mrs Lim also reiterated that the two companies are long-term investors, and should be evaluated as such.

'This is not the first major decline in markets that they have seen, and will certainly not be their last,' she said.

Despite the booms and busts over the years, Temasek has achieved annualised returns of about 13 per cent over the 20 years to late 2008.

GIC's 20-year average return was 5.8 per cent as at March last year. While this figure will fall for March this year, it 'will not be sharply down', Mrs Lim said.

'GIC and Temasek have the ability and resources to weather the ups and downs, over multiple economic and market cycles,' she added.

'They do not have to sell in panic in a market downturn and are in fact in an advantageous position to invest in good quality assets at prices that are attractive from a long-term perspective during a downturn.

'The Government is confident that they will continue to deliver good long-term returns within the risk limits set.'