WASHINGTON (REUTERS) - The Pentagon shrunk the size of its delegation travelling to next week's Singapore Airshow and US defence firms Lockheed Martin Corp and Raytheon Co said they would not attend, as the impact of the coronavirus has reduced participation in the event.

Undersecretary of Defence Ellen Lord will no longer attend the event "due to extenuating circumstances", Lieutenant Colonel Mike Andrews said in a statement.

Ms Lord is the Pentagon’s chief weapons buyer and was the Pentagon’s lead representative at the event. Other Pentagon leaders including uniformed military officials plan to attend.

Lockheed Martin became the first major US defence company to announce it will not attend the airshow due to the coronavirus.

"Following the Singapore Ministry of Health's Feb 7 declaration of a Code Orange health alert, we consulted with the US government and our medical teams and decided not to participate in the Singapore Airshow," the company said in a statement.

"We determined this was in the best interest of our employees and aligned with the US Department of Defence's decision to reduce its presence," it said.

Raytheon also pulled out.

"Because of the growing health crisis in the region, and out of an abundance of caution, Raytheon Company will not be exhibiting at this year’s Singapore Airshow," it said in a statement.

The airshow, organised by Experia Events, is an aerospace and defence exhibition held once every two years.

Earlier, it was announced that the event from Feb 11 to 16 will go ahead as planned despite the withdrawal of 16 exhibitors and fewer visitors being expected.

Experia Events said the show will see enhanced precautionary measures taken "to safeguard the well-being and safety of all attendees", in view of the evolving coronavirus situation.

The measures include additional temperature screening at access points at the Singapore Expo and Changi Exhibition Centre, as well as the provision of hand sanitisers and a team of doctors and medics to attend to visitors who are feeling unwell.