OTTAWA - The Harper government's fourth stimulus update will reveal Thursday that more than 40 per cent of the projects announced under the flagship Infrastructure Stimulus Fund are underway, The Canadian Press has learned.

The $4-billion fund, which requires matching cash from provincial and municipal governments, has approved 3,226 projects across the country, said a spokesman for Transport Minister John Baird.

Of those projects, 1,390 -- or 43 per cent -- accounting for $1.4 billion in federal funding have moved beyond the announcement stage and have started work, Chris Day said.

The government considers a project to be underway as soon as it is put up for tender, he added -- so the public may not see construction crews at work, but new jobs will be created through design and engineering.

The Infrastructure Stimulus Fund is the largest of about 40 funds in the government's $16-billion stimulus arsenal.

Finance Minister Jim Flaherty will provide an update on the total stimulus package in Winnipeg.

A federal source said Flaherty will show that in total, 12,000 stimulus projects have been announced to date, through a broad range of programs. Of those, 8,000 are underway.

The pace of work on the projects is of vital importance to the federal government's plan to revitalize the economy. The Harper administration has staked its fiscal reputation on the ability of the stimulus plan to quickly create or maintain almost 200,000 jobs across Canada.

A fast and efficient rollout of the programs is essential to creating those jobs while the workforce needs them.

Under an agreement negotiated with the Liberals last spring, Flaherty is obliged to submit quarterly updates on how the stimulus program is working.

But the parliamentary budget officer has complained that the updates released so far are so lacking in detail and inconsistent in their format that they are not very useful.

In his last update, Flaherty said 90 per cent of the government's stimulus plan had been rolled out -- a claim refuted by the Liberals, who said only 12 per cent of the plan was actually involved in work.

The Liberals also complained on Tuesday that the government is sitting on important job creation data, because it is embarrassed at how few jobs have been created by the stimulus program so far.

Government officials have said they do not track the number of jobs created by the stimulus program, even though one of the key goals of the program is to put people back to work. But the Liberals have produced documents showing that the government does collect such data -- it just hasn't released it.

An independent investigation by The Canadian Press has shown that stimulus money was not targeted at areas of high unemployment. Rather, it has favoured ridings held by Tory MPs.