Iran's oldest social media network announced Monday it is shutting down after years of battling censors, saying they had allowed foreign sites such as Instagram to take over. 

Cloob website was launched 12 years ago as the Iranian answer to Facebook and Google's now-dead Orkut, and at its peak had some two million users in the country.

But the challenge of monitoring the deluge of photos from women not to show hair and removing politically sensitive comments led to frequent clashes with the authorities. 

"Cloob.com was entirely blocked three times and the last time it took 28 days to unblock it," said company director Mohammad Javad Shakouri Moghadam in a blog post. 

"Like a farmer, a webmaster knows how hard it is to rejuvenate a land that has dried up for 28 days," he wrote, adding that his team no longer had the "energy or enthusiasm" to keep fighting.

Iran banned Facebook primarily due to lack of oversight, especially women sharing photos of themselves without a headscarf, which is illegal under the country's Islamic laws. 

But sites such as Instagram are not banned and have boomed in Iran, while messaging service Telegram has some 25 million users in the country.

Officials say they cannot ban popular online services as long as there is no local alternative.

"Cloob was one of the top three services in Iran but its flourishing tree has withered," said Shakouri. 

He said he also faced frequent legal battles over his other companies, such as video sharing site Aparat and streaming service Filmio.

"These days, some have started to... sue the new wave of content creators such as Aparat and other services -- a source of domestic content creation which would definitely be of benefit to our country and culture," he said. 

President Hassan Rouhani was re-elected in May promising to soften social restrictions. 

He appointed the Islamic republic's youngest-ever minister, 36-year-old Mohammad-Javad Azari Jahromi, to head the communications portfolio. 

Jahromi said in August that negotiations were underway to lift a ban on Twitter, though no progress has since been announced.