HONG KONG (BLOOMBERG) - Firms across Hong Kong have urged workers to consider staying home to ensure their families' safety as protests rage.

Citigroup warned its Hong Kong staff to steer clear of dangerous places after police grabbed one of its investment bankers off a pavement.

On a conference call on Wednesday (Nov 13), Citigroup said that safety was the priority amid escalating clashes between protesters and police, people familiar with the situation said, asking not to be named because the matter is private.

One of its bankers is the person seen in a video that has circulated widely on social media, according to the people.

It shows a trio of officers surrounding a man in a covered walkway. He tries to break away, at one point grabbing and swinging one of their batons as they wrestle him to the ground. As officers pile onto the man, a voice - possibly his - can be heard shouting "Hong Kong people, resist!"

Hong Kong police can arrest and hold suspects before formal charges are made. It's unclear whether the banker has been charged and the police said they couldn't immediately comment on Thursday.

"We are aware of this incident and are investigating further," said Mr James Griffiths, a spokesman for the New York-based lender.

"While investigations continue it would be inappropriate to comment further. We expect all our employees to abide by the law."

In a flurry of safety memos - which have become a part of daily life at big banks in the Asian financial hub - executives at a number of firms expressed a heightened level of caution this week after skirmishes repeatedly erupted in the streets during work hours this week, sometimes directly outside office doors.

"Where meetings are already planned, managers should not hesitate to cancel and reschedule depending on the evolution of the situation," BNP Paribas SA told employees.

Standard Chartered also advised staff to reschedule meetings and travel as appropriate, a Hong Kong-based spokesman said in an e-mail.

At JPMorgan Chase & Co's main Hong Kong offices, where some of this week's biggest clashes between pro-democracy protesters and police have taken place just steps away, employees were reminded to feel empowered to make arrangements "in circumstances that require flexibility (e.g. family needs, school closures, transport issues)".

The New York-based bank's chief executive officer of Hong Kong operations, Mr Filippo Gori, wrote in the memo: "I wanted to make sure that it was well understood given the circumstances.

"Thank you for pulling together and supporting each other, and our clients, during what has been a difficult period in the city."

Firms are trying to operate normally despite intensifying demonstrations since a student died last Friday of injuries suffered near a protest.

The main challenge for many bankers and traders is simply getting to work, as protesters impede rush-hour traffic, closing subway stations and halting bus lines. Those who made it in have faced tear gas on streets at lunch and another challenge getting home.

Then on Wednesday afternoon, the government announced for the first time that it would close public schools.

HSBC Holdings encouraged employees to work remotely if possible and to stay in touch with managers - a message echoed by others.

"All staff should exercise due care while commuting, remain vigilant of their surroundings and check travel plans before leaving for the office," Deutsche Bank told employees in a text message.