Phnom Penh: Cambodian Prime Minister Hun Sen has ordered the release on bail of more than 70 opposition activists arrested in recent weeks and accused of plotting to overthrow the government, he said on Thursday.

Hun Sen, who has ruled Cambodia for more than 34 years, has been under increasing international pressure to improve his human rights record, with the European Union threatening the withdrawal of important trade benefits.

"There are over 70 people, please hurry up work on this case so that these brothers can be released on bail," Hun Sen said in a speech at a new cement factory in the southern province of Kampot.

It comes as his government claimed victory on Wednesday in its jousting with exiled opposition leader Sam Rainsy, who was unable to meet his self-imposed deadline to return to the country.