Deliveries set for two continents simultaneously with North America were a first for the Palo Alto, California-based company and the associated stress is something that will not be repeated in subsequent quarters, Musk said in the email seen by Reuters.

Tesla declined to comment further.

"What has made this (delivery targets) particularly difficult is that Europe and China are simultaneously experiencing the same massive increase in delivery volume that North America experienced last year," Musk said.

The delivery rate per day is over 600 percent higher than its previous peak, Musk said.

Reuters reported in February that the company's job cuts in January particularly hit the delivery team that supplied electric vehicles to North American customers, indicating a slow pace of deliveries in the near term.

(Reporting by Supriya Roy in Bengaluru and Alexandria Sage in San Francisco; editing by Grant McCool)