Well that didn't last very long.

Within 12 hours of its official launch yesterday the US "Virtual" Embassy Tehran was blocked by Iranian authorities. The English and Farsi versions went live at 6a Eastern time yesterday and by 5pm both were blocked inside Iran.

The semi-official Fars news agency quoted a spokesman for Iran's Foreign Ministry as claiming the site meddled in the country's domestic affairs.

The State Department today said they expected as much.

"The fact that they would - in fact, the Iranian government would attempt to block access to a site that… does nothing more other than offer information about how to travel to the United States and opportunities for travel to the United States, as well about our policies, in a very transparent and straightforward manner, speaks volumes about their trust in their own citizens," deputy spokesman Mark Toner told reporters.

The State Department officials said they have data showing that some in Iran are still able to access the sites. Many Iranians use virtual private networks, or VPNs, to access blocked sites like Facebook. A VPN routes a user's internet access through another location, thereby bypassing the state controls by accessing the blocked content from a different source.

Since their launch yesterday both sites have seen about half a million hits, most from outside Iran. According to the State Department the English version saw 2001 unique users coming from within Iran, and the Farsi version saw 7,770.

"We've also been in contact with our firewall team at the hosting company and have seen no indication that the site's been violated," Toner said.

The sites can be accessed in English here and here and in Persian here.

The sites contain information for students and Iranians wishing to study or visit the United States, as well as information about US policies. The homepage features a welcome video by Secretary of State Hillary Clinton, who announced the creation of the site in October during interviews with the Persian-language services from the BBC and Voice of America.

"The virtual embassy is a hub in Persian and English for information not only on U.S. policy towards Iran but also a place to get insight into American culture and society, find visa applications, learn about opportunities to study in the United States," Under Secretary of State Wendy Sherman said yesterday shortly after the sites launched.

She described the website as an effort to get around Iran's attempts to impose "an electronic curtain by disrupting cell phones, the internet, and social media."

She predicted that Iran would try to block access, telling reporters "we'll continue to do whatever we can. We think we have the technical capability to get it back up even if it gets disrupted, and we're committed to doing everything we can to make sure the information gets through."

ABC News' Luis Martinez contributed to this report.