Ottawa-area landlords are expressing frustration over high vacancy rates for rental units, a day after the province announced a cap on rent increases.

John Dickie, chair of the Eastern Ontario Landlord Organization, estimates there are roughly 4,000 empty or soon-to-be empty apartment units in the capital.

In Ottawa, the vacancy rate has risen from 2.1 per cent in April last year to 3.7 per cent this April.

"We think it's because of some uncertainty around the federal government job situation," said Dickie.

The rental market vacancy rate is calculated by looking at apartments in buildings that are three units or larger, and does not include condos or homes for rent.

Cap could impact repairs, landlords say

But some analysts suggest the increase of condo rentals could be contributing to the high vacancy rate, as condo units compete with traditional apartments.

Ontario announced Thursday it is capping rent increases for 2014 at 0.8 per cent, the second lowest cap since the introduction of rent regulations in 1975

Dickie says on top of high vacancy rates, that creates another problem for landlords.

"It makes it difficult for landlords to do repairs and renos," he said. "When the government limits the rent increases, landlords are forced to limit repair costs."