The meeting at the Institute of Directors was brought to an end after a protester dressed as Santa Claus delivered a sack of coal to the GCM chairman, Gerard Howell. Two protesters were arrested for breach of the peace but released without charge.
The firm, listed on London's junior Aim market, wants to run an open pit coal mine in the Phulbari township in the north of the country, despite claims that up to 130,000 people could be displaced and warnings by the UN that human rights could be violated.
An official complaint to the Organisation for Economic Co-operation and Development has been made by the World Development Movement and the International Accountability Project, saying the company would forcibly evict up to 130,000 people if the project went ahead. The complaint mentions a UN report from earlier this year warning that "access to safe drinking water for some 220,000 people is at stake".
The company claims the mine will displace 40,000 people but create 17,000 jobs.
The 1,000ft-deep mine, which could stretch across 14,500 acres has been put on hold since 2006 after local opposition.
According to documents released under the Freedom of Information Act, GCM bosses have approached Britain's Department of Trade and Industry to soothe relations between the company and the Bangladeshi government.
In 2006, three people were killed and 800 injured at the mine during protests about the possible evictions. GCM said development of the mine was essential for meeting Bangladesh's energy needs by providing about 114m tonnes of coal for domestic consumption with the remaining 458m tonnes sold abroad.