LONDON, March 4 (Reuters) - An election pledge from Britain's opposition Conservatives to cut taxes on company profits came under fire yesterday from a senior tax counsel at General Electric (GE) and from a free-market think tank.

The Conservatives, seeking to end 13 years of Labour rule in an election that must take place by June 3, propose cutting the headline rate of corporation tax for big firms to 25 from 28 percent, and for small firms to 20 from 21 percent.

The cuts, presented as a business-friendly measures to help make Britain more competitive, would be funded by scrapping complex allowances and tax reliefs for companies.

But at a debate in London yesterday on reforming Britain's tax system, William Morris, senior international tax counsel at US conglomerate GE, advised the Conservatives to drop the pledge.

"What large businesses need now is stability," Mr. Morris said.