Around 40 people have been injured in Vietnam during a protest against the 3-month detention of two Catholics on minor charges.

The protest on Sept. 4 in Nghi Phuong, south of Hanoi, was a response to the police refusal to release Nguyen Van Hai, 43, and Ngo Van Khoi, 53, who were arrested May 22 for "disturbing the public order".

Protesters claimed the police had promised the duo's release by Sept. 4, although police later denied this claim. Tear gas, batons and police dogs were used to disperse protests. Around 15 protesters were arrested.

On Sept. 8, the Federation of Vietnamese Catholic Mass Media released a statement condemning the government's role in ordering the harsh police response.

"The laws of Vietnam have become an effective means for the authorities to use whenever they want to suppress their own people," the statement read.

Vietnam is No. 21 on the 2013 World Watch List, an annual ranking of the 50 countries where life as a Christian is most difficult. It is published by Open Doors International, a ministry to Christians living under pressure for their faith.

"In the coming years, it is unlikely that the situation will change substantially in favour of the Christian minority.

Authorities have started to place more restrictions on areas that have experienced a more 'lax' approach from the government for years," reports the List.

Of the country's approximate 9.7 million Christians, more than 8 million are Catholics.