The New Millennium Experience Company, which runs the attraction, said just over 500,000 people visited the site last month, with an average 16,200 people passing through the turnstiles every day.
The dome needs to attract an average of more than 20,000 people every day to reach the target which was brought down last month from a break-even figure of 10m visitors.
When the £758m attraction opened to the public in January, the NMEC hoped to draw 12m people over the year.
Last month's disappointing attendance figures - the worst since January - come after the NMEC was forced to seek a cash lifeline from the Millennium Commission, which has already given more than £500m to the beleaguered attraction.
However, Pierre-Yves Gerbeau, the NMEC's chief executive, was yesterday upbeat about the the dome's prospects of meeting its revised target. "We are well on our way to achieving our new, realistic, target of 7m visitors," said Mr Gerbeau, who believes figures will be boosted by an influx of tourists and schoolchildren over the summer.
He added: "By any standards the dome is clearly an overwhelming success both in terms of visitor numbers and the positive feedback from those who visit."
At last month's crisis meeting the lottery commission granted £29m lottery money to the dome on the condition that Bob Ayling, the NMEC chairman resigned. Last Wednesday, Mr Ayling was replaced by David Quarmby, chairman of the British Tourist Authority and Docklands Light Railway.
Under plans to save money, many of the 5,500 staff could lose their jobs, and executive salaries and perks are likely to be cut. The dome has now scrapped its 11pm late-night opening on Fridays, Saturdays and Bank Holidays. It is open from 9am to 8pm each day with half-price £10 tickets available on the doors after 4pm.
To reach the target of 7m visitors, the dome will need to attract just under 145,000 visitors a week or more than 632,000 a month.
Until the end of May, the dome attracted an average of 17,045 visitors a day which worked out at just under 515,000 a month. The best month for the dome so far has been April when 579,333 visited. The numbers were boosted by the Easter holidays.
The NMEC said yesterday that the attraction, in Greenwich, south-east London, will next week beat last year's attendance figure for the most popular charging attraction in Britain. Alton Towers theme park in Staffordshire attracted 2.65m people.
To the end of May, 2,573,803 people had visited the dome, but the figure includes thousands of schoolchildren who have been let in free.
