Vince Cable has become embroiled in a row over regional pay after allegedly telling union members that he is "against" the move, pre-empting a Treasury report into the matter.
The Business Secretary met protesters from the Public and Commercial Services union at his Twickenham constituency office.
The union had been protesting outside the offices of Mr Cable and Cabinet colleagues Francis Maude, Michael Gove and Iain Duncan-Smith as part of the continuing campaign against the Government's pension reforms.
Between 10 and 30 union members at each location, who were also constituents, held placards and handed out leaflets on pension reform.
Keith Johnston, of the Public and Commercial Services union, said: "The only one where the minister agreed to be there and meet with his constituents who are our members was in Twickenham.
"Cable did meet us. He said that he was opposed to plans for regional pay. On pensions issues he said he would take our views back with him and give them to [Treasury Secretary] Danny Alexander.
"How much influence the Lib Dems have I do not know, but it was encouraging."
The Treasury is examining whether to bring in local pay variations for civil servants.
Sources close to Mr Cable stress that these are not 'regional' pay programmes and his support for the Government's local programme is not tempered by his rejection of broader regional pay.
Mr Cable has previously spoken out to promise that the Government will not "impose" lower pay on public sector workers in the regions.
Speaking in Cardiff earlier this month he told workers at a steel recycling plant: "There is no question whatsoever of average low pay across Wales in the public sector being imposed from central government."