The UK Government will today reveal details of its multibillion-pound plan to tackle Aids and HIV in developing countries across the next six years.

The UK Government will today reveal details of its multibillion-pound plan to tackle Aids and HIV in developing countries across the next six years.

But the Department for International Development (DFID) has already drawn criticism over its £6bn investment pledge, with a cross-party group of MPs dismissing the plan yesterday as "strong on rhetoric" but weak on details.

The International Development Committee said it "wholeheartedly" supported the spending commitment, but warned that further information was necessary if the work was to be successful.

The group said in a statement: "There are few measurable targets or indicators of how the strategy's effectiveness will be assessed.

"DFID fails to explain how the high-level funding commitments will be broken down by country or sector, making it difficult to understand how implementation will occur on the ground."

DFID promised to spend £6bn between now and 2015 on halting the spread of Aids and HIV in poorer countries. The government strategy aims to provide universal access to HIV prevention, treatment and care within the next two years.

Douglas Alexander, Secretary of State for International Development, said efforts would be targeted at those most affected by the growing crisis.

Speaking before today's World Aids Day, he said: "Preventing people from becoming infected with HIV is the best hope we have of stopping the pandemic that we are facing around the world at the moment.

"The UK will be focusing our efforts on prevention, addressing vulnerable people such as children and mothers, and intensifying these prevention efforts by dealing with issues like child transmission, family planning and harm reduction."

DFID will provide £200m for protection programmes to help children who have been orphaned or made vulnerable by HIV or Aids, with more than 12 million children in Africa alone having lost one or both parents to the infection.

International Development Minister Ivan Lewis highlighted the UK's exemplary record in tackling Aids, and promised the new funding would go to the world's least developed countries.

"We are rightly proud of the fact the UK is widely acknowledged as a world leader in the fight against HIV and Aids," he said.

"Between now and 2015 the UK will invest £6bn to ensure countries with the least developed health systems can fight and win the battle against Aids. On Monday, we will be publishing details of a new approach to measuring the effectiveness of our investment in Aids programmes."

However, the International Development Committee called for more details on where the public money was going.

Malcolm Bruce, a Liberal Democrat and the committee's chairman, said: "It is not yet clear to us whether this £6bn is new money or simply a redirection of existing commitments.

"We have asked the department for a full breakdown of where this sum will come from and how it will be spent on the ground in developing countries."

He added that the strategy also lacked sufficient details on the UK's commitment to fighting gender-based violence, a key reason for HIV having a disproportionate impact on women and girls.

"We were shocked to learn that young girls in some countries in Africa are more likely to be raped than to learn how to read and write," he said.

"Sexual violence is a major factor in the spread of HIV. We need to know what programmes DFID intends to support to tackle gender-based violence."

World Aids Day is being marked with demonstrations around the world. Some 33 million people are currently living with Aids, and nearly 7000 new infections are recorded every day.

Though areas in sub-Saharan Africa are among the worst affected, infection rates in the UK have trebled in the past 10 years. An estimated 77,400 people in this country have Aids, of whom more than one-quarter do not know they are infected, according to the Red Cross.