Police in Nicaragua have arrested a seventh presidential candidate ahead of the November 7 election.

Noel Vidaurre was placed under house arrest and charged with "undermining the sovereignty" of the country.

Vidaurre is now one of the latest victims of the wave of arrests in which a total of 28 opposition members have been jailed since the beginning of last month.

They are charged with undermining the "sovereignty and independence" of the country, on the basis of a controversial law that critics say is designed to silence opponents of President Daniel Ortega.

One of his arrested opponents, Cristiana Chamorro, was given a good chance of winning the election.

Ortega, 75, is expected to start his fourth term since 2007 after the vote.

The former left-wing revolutionary claims that "criminals" want to oust him from power with American support.

The arrests have previously garnered a wave of international criticism, with Washington calling for Ortega to be treated as a dictator.

See also: Nicaragua parliament excludes opposition members from elections