 -- With multiple doctors and medical students affected by President Trump's executive order to restrict immigration and visas from seven Muslim-majority nations, physicians' groups are warning about the potential for long-term detrimental effects on the medical community.

The American Medical Association on Wednesday issued a statement expressing worry about how the executive order could adversely affect the U.S. health system overall, especially because international medical graduates are more likely to work in underserved areas.

"The AMA is concerned that this executive order is negatively impacting patient access to care and creating unintended consequences for our nation's health care system," Dr. James Madara, the AMA's chief executive officer and executive vice president, said in the statement.

"Specifically, there are reports indicating that this executive order is affecting both current and future physicians, as well as medical students and residents who are providing much needed care to some of our most vulnerable patients," he added.

The New England Journal of Medicine published multiple opinion pieces on Wednesday from doctors and researchers concerned about how the executive order might alter how medical institutions pick doctors for residencies or fellowships and how the ban could stop some medical researchers in the U.S. from sharing their work abroad.

In one piece, authors from the University of Pittsburgh Medical Center argued that the ban could seriously affect rural or underserved communities. Many foreign physicians trained in the U.S. are able to stay in the country by agreeing to a J-1 waiver, which often leads to work in underserved rural or inner city areas, according to the authors.

"Physicians with J-1 waivers are filling clinical jobs in areas of need," the authors wrote.

They added that the executive order comes as medical institutions are preparing to match medical students with residency positions in hospitals. Medical students and residents generally apply for residencies or fellowships in the fall and find out if they have matched with an institution in March.

The AMA in its statement requested clarification from the Trump administration about whether the match program will be affected.

"Guidance is urgently needed from the administration to ensure the upcoming residency matching program in March 2017 does not leave training slots vacant and that all qualified IMG [international medical graduate] applicants can participate," Madara said.

According to a statement provided to ABC News, the Association of American Medical Colleges estimated that 1,000 people applying for residencies and fellowships in the U.S. will be affected by the executive order.

"The nation's medical schools and teaching hospitals are dedicated to promoting a diverse and culturally competent health and biomedical workforce that supports improvements in health care, breakthroughs in medical research and, ultimately, improved and equitable health for all patients," AAMC officials said in a statement on Monday. "We are deeply concerned that the Jan. 27 executive order will disrupt education and research and have a damaging long-term impact on patients and health care."

Dr. Ahmad Masri, a co-author of one of the NEJM pieces and a cardiologist at the University of Pittsburgh Medical Center, said the executive order will mean that affected doctors will likely avoid traveling to medical conferences outside the U.S., interrupting the normal flow of information among researchers.

"Many people are canceling [trips to] conferences, and it's affecting how the U.S. is being perceived in the international community," he said.

In another NEJM opinion piece, doctors from institutions like Massachusetts General Hospital and Brigham and Women's Hospital in Boston explained that the ban could have a significant impact on the how the medical community can work together.

"Today, international collaborators are the bedrock of many of our most important scientific endeavors, from genomics to drug development," the authors wrote. "Given the access to global talent, it is perhaps not surprising that internal medicine faculty in the top U.S. departments now come from many countries."