British Columbia's Liberal government, which is on the verge of being voted out of power, said on Wednesday its unaudited 2016-17 budget surplus was $2.8 billion (US$2.15 billion), sharply above the $1.5 billion it projected in February.

Michael de Jong, the Western Canadian province's finance minister, said the larger surplus was driven by higher-than-expected economic growth, marked by strong employment, retail sales and housing starts.

Preliminary real 2016 GDP growth came in at 3.7 per cent, ahead of a budgeted 2.4 per cent.

"British Columbia saw the strongest economic growth among the provinces (of Canada) last year and some of the fastest job growth in more than 20 years," de Jong said in a statement.

The fiscal update is usually only released in July, and once the figures have been audited. Government critics say the early release is an attempt by the Liberals to burnish their credentials as they prepare to leave office.

The Liberals are expected to be defeated on Thursday in a non-confidence vote brought by the left-leaning New Democrats and backed by the Green Party. The Liberals, in power for 16 years, lost their majority in a May election.

But with only one seat more than the Liberals in the legislative assembly, an NDP-Green government could become unworkable, resulting in a new election being called.