BEIJING:China's embassy in Afghanistan warned its companies and citizens on Friday not to "blindly" visit the country to inspect mineral resources, after reports of foreigners being detained without exploration permits.

Afghanistan's Ministry of Mines and Petroleum has "extremely strict" standards for issuing permits for prospecting for minerals, the embassy said, adding that companies and individuals that do this without a permit risk being detained.

"Currently there have been many incidents of foreign citizens being detained without permits in various parts of Afghanistan," it said in a statement on its website.

Afghanistan was estimated by a former mines minister in 2010 to have untapped mineral deposits worth between $1 trillion and $3 trillion, ranging from copper to gold and rare earths, but it is not clear how much those resources are worth today.

It also has large reserves of lithium, a key component used for the batteries of electric vehicles, but it still lacks much of the necessary infrastructure to mine it.

Western miners have said the recent change in government in Afghanistan would deter investment in the country. The Taliban took over the country in August, leading to an abrupt withdrawal of foreign aid that has left Afghanistan's fragile economy on the brink of collapse and facing increased insecurity.

Representatives of several Chinese companies visited Afghanistan last month on specially arranged visas to inspect potential lithium projects, the state-backed Global Times reported in November.

China is the world's top consumer of minerals and has invested in projects in many of the world's resource-rich countries, including Afghanistan.