San Francisco, April 13 (IANS) Facebook spent $20 million on its CEO Mark Zuckerberg's personal security last year -- four times more than what he received for security in 2016.

In a filing with the US Securities Exchange Commission (SEC) on Friday, Facebook said it spent $2.6 million on private plane costs -- up from $1.5 million a year before, CNET reported.

The aircraft expenses went to charter companies and included "passenger fees, fuel, crew, and catering costs".

Zuckerberg takes $1 as salary each year but his total compensation was $22.6 million in 2018 -- more than double since 2017 when he made $9.1 million in total compensation.

Facebook spent $2.9 million on personal security for its COO Sheryl Sandberg. The social networking giant spent more than $900,000 on her private plane costs.

The hike in security expenditure for its leaders is owing to Facebook facing the heat for growing cases of election interference and data misuse on its platform.

"Because of the high visibility of our company, our compensation and governance committee has authorised an 'overall security programme' for Zuckerberg to address safety concerns due to specific threats to his safety arising directly as a result of his position as our founder, CEO, Chairman, and controlling stockholder," read the company document.