The Food and Drug Administration (FDA), Monday, requested more information from GlaxoSmithKline before they would approve its Cervarix cervical cancer vaccine.

Cervarix protects girls and women against two strains of the sexually transmitted human papillomavirus that causes cervical cancer. The vaccine was approved by European regulators in September and is currently approved in 45 countries, including the 27 member states of Europe.

The vaccine will be delayed in the United States most probably for up to two years, which led to a fell of 2 percent at $51.60 on Monday in the U.S. shares in GSK. On the other hand, the competitor vaccine Gardasil belonging to Merck &Co is already well established in the U.S.

Europe’s biggest drug producer said that the FDA had asked for a “complete response” letter with more information about Cervarix before the vaccine ccould be approved. It also said that the company would respond as soon as possible.

"We have already started addressing the questions and will be engaged in discussions with the FDA to finalise our responses," Said Barbara Howe, director of north American vaccine development at GSK, according to the Independent.

According to analysts at Panmure Gordon, the problem with vaccine could be in the chemistry, manufacturing and control and could lead to a delay from six months up to two years if new data were required.

GSK is not at its first struck on the drug market. Earlier this year, the company’s blockbuster diabetes drug Avandia lost more than half its U.S. sales after a report, which linked its use to an increased risk of heart attacks. Therefore, Cervarix is seen as a vital drug for GSK’s growth as it looks for new medicines to replace older drugs, which are coming towards the end of their patent.

Analysts believe that Cervarix can generate 70 million pounds for GSK in 2008 , 177 million pounds in 2009 and up to 214 million pounds by 2010.

Gardasil brought in 207 million pounds for Merk in the third quarter of 2007.

Cervical cancer is the second most common form of cancer among women after breast cancer. Almost 250,000 people suffering from this disease die every year, according to the World Health Organization.