SAN FRANCISCO, United States (AFP) — US business leaders are calling for calm following today’s election even as they brace for potential trouble on the streets and inside their companies in case of a disputed result.

The fears were highlighted in many US cities where retail stores were being boarded up, as some key executives expressed concerns about public reaction.

Facebook chief Mark Zuckerberg last week warned of the potential for civil unrest as votes are tallied in a US election that will be “a test” for the social network.

Zuckerberg expressed his concern recently while describing safeguards against misinformation and voter suppression at the leading social network that are intended to avoid the kinds of deception and abuse that played out four years ago.

“I’m worried that with our nation so divided and election results potentially taking days or weeks to be finalised there is a risk of civil unrest,” said Zuckerberg.

American companies are striving to maintain the appearance of political neutrality while they ramp up security and watch for clashes between employees with conflicting political views in an election so hotly fought it is at a flashpoint.

The risk appears heightened amid concerns that President Donald Trump may challenge the validity of the results of the race against Democrat Joe Biden.

“This has been a difficult election for a lot of companies to navigate,” Control Risks associate director Allison Wood told AFP.

The business risk consulting firm has seen an uptick in requests for additional security, both armed and unarmed.

While retailers have been most interested in the potential of looting or rioting, operations with around-the-clock shift workers are worried about trouble in the streets preventing employees from showing up, according to Wood.

Companies are also worried that polarising political themes fuelling conflict in the streets will ignite clashes on factory floors or in other facilities.