WASHINGTON (AFP) - US factory orders fell for a fifth straight month in December, hit by the global economic slowdown and the oil price plunge, US Commerce Department data released Tuesday showed.

New orders for manufactured goods fell 3.4 per cent from November to US$471.5 billion (S$632.4 billion), with shipments, unfulfilled orders and inventories also all lower.

The decline was spread through a broad range of industries.

Excluding the often-volatile transport sector - cars, trucks and aircraft mainly - new orders fell 2.3 per cent.

The data underpinned a general easing in US economic activity at the end of last year, which held overall growth in the final quarter to a 2.6 per cent annual pace.

Behind that are a number of factors, including pullbacks in the oil industry due to the plunge in crude prices; the dollar's climb, making US exports more expensive; and the general economic weakness abroad.

"It is hard to put a positive spin on the weakness in Q4 factory orders, as it likely points to a slowdown in business activity in the current quarter extending beyond the oil industry," said Jay Morelock and Chris Low of FTN Financial in a client note.

"This weakness won't necessarily translate into weaker real GDP, but it will affect corporate revenue and profit figures," they said.