WASHINGTON — Since President Obama took office, the federal government has poured more than $29 billion into health information technology and told doctors and hospitals to use electronic medical records or face financial penalties.

But some tech companies, hospitals and laboratories are intentionally blocking the electronic exchange of health information because they fear that they will lose business if they share information on patients with competing providers, administration officials said. In addition, officials said, some sellers of health information technology try to “lock in” customers by making it difficult for them to switch to competing vendors.

“We have received many complaints of information blocking,” said Dr. Karen B. DeSalvo, the national coordinator for health information technology. “We are becoming increasingly concerned about these practices.”

The White House and Congress are looking for ways to ensure a freer flow of information.

Mr. Obama has made computerizing patients’ medical records a priority of his administration. Four weeks after taking office, he signed an economic stimulus bill that offered bonus payments to doctors and hospitals adopting the new technology. He said that it would save money by reducing waste and duplication, and that it could save lives by improving care.