About 20 senior citizens have sent Queensland's government headquarters into lockdown with their protest against the Adani coal mine.

A spokeswoman at 1 William Street said the protesters entered the foyer with hidden banners about 11am on Monday.

Adani protesters are seen occupying the foyer of the Queensland government headquarters at 1 William Street. Credit:AAP

Ten police were negotiating with the group, which was demanding a meeting with Environment Minister Leeanne Enoch.

They wanted assurances the government would prosecute Adani over an alleged breach of its pollution licence for releasing sludge into wetlands near the Great Barrier Reef in 2017.