A document drawn up by the two parties states: ‘The parties will tackle lobbying through introducing a statutory register of lobbyists'.
The seven-page document, entitled ‘Coalition negotiations - agreements reached', provides no further details on the plans for a statutory register.
The move represents a climbdown by Tory leader David Cameron.
The Liberal Democrats have long been in favour of such a register. In the run-up to the 2010 election campaign, Labour also pledged to implement a statutory register of lobbyists, but the Conservatives refused to endorse the idea.