US Vice President Joe Biden's remarks on avoid contracting swine flu by staying out of airplanes made on Thursday triggered controversy as the pandemic continued to spread in the country.

Biden said in an interview with the NBC's "Today" show that he would tell his family members not to "go anywhere in confined places now," since one person's sneeze "goes all the way through the aircraft."

"I would not be, at this point, if they had another way of transportation, suggesting they ride the subway. So from my perspective, what it relates to is mitigation," he said.

"If you're out in the middle of a field and someone sneezes, that's one thing. If you're in a closed aircraft or a closed container, a closed car, a closed classroom, it's a different thing," he added.

For fear that his remarks would stir up panic in the country that is gearing up for the outbreak of the swine flu, and complaint from the airlines industry, Biden's office issued a statement of clarification immediately after the show was broadcast.

A vice president spokeswoman said that Biden made the remarks when he was asked about the flights to Mexico.

"The advice he is giving family members is the same advice the administration is giving to all Americans: that they should avoid unnecessary air travel to and from Mexico," she said.

"If they are sick, they should avoid airplanes and other confined public spaces, such as subways. This is the advice the vice president has given family members who are traveling by commercial airline this week," she added.

White House spokesman Robert Gibbs also said at the press conference that the vice president had meant to stress a specific warning against non-essential travel to Mexico.

"I'm apologizing to those who were unduly alarmed," he told reporters.

However, the Air Transport Association of America (ATA) sent a letter to Biden to express its "extreme disappointment."

"The fact is that the air on board a commercial aircraft is cleaner than that in most public buildings," ATA President James May wrote, adding "we need to deal responsibly with the flu threat" while also keeping the economy moving.

Roger Dow, the president of US Travel Association, also urged public officials not to make "inflammatory" remarks at a time of public fear.

"Elected officials must strike a delicate balance of accurately and adequately informing citizens of health concerns without unduly discouraging travel and other important economic activity," he said.

The US government confirmed on Thursday that there have been more than 100 swine flu cases in the country.

(Xinhua News Agency May 1, 2009)