Online fashion firm Boohoo has raised its full-year sales outlook after posting a 51% hike in first-half profits amid a furore over allegations of low pay and poor working conditions for factory staff.

The group reiterated a pledge to make “long-lasting and meaningful change” to the business after a damning report last week found “serious issues” in its supply chain.

Boohoo, which accepted the recommendations in the review and set out steps to improve working practices in the Leicester factories, insisted when unveiling half-year results that it can make the changes “without impacting lead times or financial expectations”.

The figures show pre-tax profits jumped to £68.1 million in the six months to August 31, up from £45.2 million a year earlier, and Boohoo now expects annual sales to jump by 28% to 32% against the 25% hike it previously pencilled in.

It also nudged up guidance for profit margins to around 10% for the year from 9.5%-10% previously.

Boohoo said robust trading continued into September in a “good start” to the second half of its financial year.

But it said: “At this stage we feel it is prudent to continue to plan for a period of economic uncertainty in the second half of the financial year, including possible reduced consumer spending.”

The firm said it is also bracing for an increase in the number of items returned, back to more normal levels, having fallen during lockdown, as well as delivery cost hikes in some overseas markets and higher marketing spend.

The half-year results showed sales jumped 37% in the UK and 44% across the group as a whole as locked-down shoppers switched spending online.

Richard Hunter, head of markets at interactive investor, said the scandal over the firm’s supply chain has “done little to harm Boohoo’s profits or prospects”.

He cautioned the group’s measures in response to the report “will, of course, come at a cost and the possibility of wider investigations cannot be ruled out”.

“However, any reputational damage caused by the allegations has not filtered through to a very strong set of numbers,” he added.