Joe Phelan was MD and executive vice-president, head of international corporate comms for the firm since November 2014, while Gary Sargent was senior vice-president, corporate comms EMEA and lead of the firm's EMEA energy practice.
A spokesman for the firm gave PRWeek an "agreed statement" that said Phelan had left on 8 April "to pursue new business opportunities", and thanked him for having "made an important and valuable contribution to the business".
The same spokesman said that Sargent departed the business at the end of March, but no further comment was given.
Phelan had been with the firm since 2010 when he joined from Bell Pottinger, and was given his most recent roles in 2014. While at Bell Pottinger he was also a contributing editor at Esquire magazine, covering politics.
Sargent arrived at Weber in January 2014, having spent 12 months before that at Regester Larkin, which he had joined from Westminster Advisers. According to LinkedIn he began his career working for the New South Wales Government in Australia. He has since advised the country's national government.
This follows the departure of the company's managing director, technology, EMEA, last month. Peter Ross had held the role since 2012, and has been succeeded by Joe Walton, a member of that practice since 2007, according to LinkedIn.