It was not immediately clear whether the slowdown would put at risk overall delivery targets for 2024 since deliveries lag output decisions by months, but the sources said assembly of several dozen jets could be delayed in the second half.
Several airlines could see individual deliveries - already running an average of 1.5 months behind schedule - further delayed, the sources said, asking not to be identified.
A spokesperson for Airbus referred back to the group's last quarterly results, in which it reiterated a 2024 delivery target of 800 airplanes, and declined further comment.
Airbus shares were down around 2% in the wake of the Reuters report, within a flat French blue-chip index (.FCHI).
By the end of April, Airbus had delivered 204 airplanes since the beginning of the year.
Airbus plans to raise underlying production of aircraft by about 50% to 75 narrowbody planes a month in 2026.
Sources have previously said it hopes that any delays can be recovered in time to meet the medium-term goal, but the available buffer for delays is shrinking.
The supply chain is responsible for up to 80% of the content of Airbus jets and stretches as much as nine layers deep.
Details of Airbus' industrial process were disclosed in legal filings during a dispute with Qatar Airways in 2022 and in conversations with sources who spoke on condition of anonymity.
Each month Airbus holds an internal meeting to match industrial production to demand several years ahead.
Parts are typically ordered 12-13 months ahead for standard narrowbody aircraft like the in-demand A321neo single-aisle, or longer for variants that require more customisation.
But lead times for some scarce parts like forgings have more than doubled to as much as two years, the industry sources said. Disruption to seat supplies remains an issue especially for wide-body aircraft, leading to delays in handling customised orders.
The rolling forecasts are translated into fixed production plans for specific aircraft for the next three months and then final adjustments are made on a monthly basis.
Suppliers said these monthly requests known as "call-offs," are being regularly deferred, which signals more delays in putting aircraft onto the assembly lines later this year.
The mounting pressure comes as airline leaders prepare for a high-profile annual summit in Dubai, with concerns about plane shortages expected to be voiced publicly for a second year running by the International Air Transport Association.
On a positive note, Airbus is increasingly confident of winning delayed certification for its A321XLR passenger jet in time for the Farnborough Airshow in July, industry sources said.
A spokesperson for the European Union Aviation Safety Agency (EASA) said it expected to certify the aircraft by the summer and declined to comment on a specific date.
