HANOI (Reuters) - Vietnamese police have detained a blogger for posting "bad content" about the state, the latest move in a crackdown on dissent that has been condemned by rights groups and Western governments.

Hong Le Tho, 65, was detained for "posting online articles with bad content and false information that discredit and create distrust among people about state agencies, social agencies and citizens," the Ministry of Public Security said on Saturday on its website.

The case follows a sharp increase in arrests and prison terms for government critics in the past few years that has alarmed the United States, a former enemy that is struggling to build a case for deeper trade ties with a country steadfast in its intolerance of dissent.

The detention of Tho, better known as blogger "Nguoi Lot Gach", came a month after Vietnam released jailed blogger Nguyen Van Hai, who staged a hunger strike to protest treatment of political prisoners.

It was unclear what Tho posted, as his blog requires an invitation in order to access it.

The popularity of political blogs has grown with increasing internet usage and simmering discontent over the Communist government's handling of a stale economy and rampant graft.

The number of web users has soared to a third of Vietnam's estimated 90 million people, and the Internet is one of only a few channels for dissent in a country where protests are rare and the media is tightly controlled by the state.

The United States has urged improvements in Vietnam's human rights record.

In an address to Congress in June, the U.S. State Department's envoy for democracy, Daniel Baer, described Vietnam's crackdown on bloggers as part of "a years-long trend of deterioration".

(Editing by Rosalind Russell)