WASHINGTON (AFP) - The US government shutdown has hampered inspectors' ability to respond to a salmonella outbreak in raw chicken that has sickened nearly 300 people, a congressional spokesman said on Wednesday.

"The shutdown has really handcuffed these regulatory agencies and their proper regulatory role," Mr Eric Walker, spokesman for Congresswoman Louise Slaughter, told AFP.

"This is the nightmare scenario, not just with the government shutdown but this is what happens when you overuse antibiotics in livestock."

The outbreak has been linked to raw chicken from three Foster Farms locations in California, according to the Centre for Science in the Public Interest (CSPI).

The consumer advocacy group also noted that seven strains of salmonella appear to be responsible for the sicknesses, which have affected 278 people in 18 states.

A high proportion of people have been hospitalized - 42 per cent according to CSPI - and some of the salmonella strains are showing resistance to antibiotics.

"The number of people we know to be ill is just the tip of the iceberg," said CSPI food safety director Caroline Smith DeWaal.

"This outbreak shows that is a terrible time for government public health officials to be locked out of their offices and labs, and for government Web sites to go dark."

Foster Farms said in a statement that no recall is in effect and that "products are safe to consume if properly handled and cooked".

The US government shutdown, which began October 1, has sent hundreds of thousands of federal workers home without pay, including staff at the Centres for Disease Control, US Department of Agriculture and Food and Drug Administration.

According to US media reports, the CDC on Tuesday recalled some of its staff to re-open a network of public health labs that monitor for food-borne outbreaks.