The London Development Agency has denied claims that spending on consultants had soared over the last year.

Figures published by mayor Ken Livingstone appeared to show that the LDA spending on consultants had risen from £3.3 million in 2002/03 to £13 million last financial year.

That data prompted Dee Doocey, Liberal Democrat spokesman on economic development in the London assembly, to say there were "serious issues about the transparency and accountability of the LDA".

But a statement released by the LDA said the figures could be explained by "the transformation in the size of the LDA and the growing scope and complexity of its activities over the last three years".

"Having been set up in July 2000, the LDA's costs on consultants during its first year or two were minimal because of the large amount of single regeneration budget projects that it inherited," said a spokesman.

"As the LDA has matured and developed, it has taken on major strategic projects such as the London Olympic bid, the development of the London Thames Gateway and the regeneration of Wembley, including Wembley Stadium."

The development body also said the lower figure for consultants had been based on the Department of Trade and Industry's definition of consultancy that excluded technical expenditure within LDA programmes.

The £13 million figure given in response to a question to the mayor in the assembly includes all LDA spending on specialist expertise.

The spokesman added that without the assistance "the LDA could not have successfully delivered projects such as the masterplanning of the Olympics zone, and the development of the London Thames Gateway investment framework".