Beximco is Bangladesh's exclusive distributor of the Oxford University-AstraZeneca shot that SII, the world's biggest vaccine manufacturer, is producing in bulk for low- and medium-income countries.
The Bangladeshi company last week received 5 million of the 30 million doses it had ordered from SII for Bangladesh's immunisation programme that begins next week.
Beximco had separately ordered 1 million doses for sale on the private market, with the hope to start marketing it this month.
"However, the company has now been informed by SII that the first instalment (500,000 doses) of this supply will be delayed following a prioritisation on supplying vaccine doses for government mass vaccination programmes and WHO-led COVAX initiatives over private pay use," Beximco said in a regulatory filing.
"It remains unclear how long this delay will last."
Beximco's chief operating officer told Reuters last month the company could buy up to 3 million doses of the vaccine from SII at about $8 each for sale on the private market.
The price is about twice the $4 per dose that Beximco had agreed for the government programme.
AstraZeneca has been embroiled in a dispute in Europe after it said it would have to cut supplies of its vaccine there in the first quarter.
The WHO has called for vaccines to be should be shared equitably and has urged countries them not to jostle for deliveries.
(Reporting by Krishna N. Das in New Delhi; Editing by Robert Birsel)