The Panel of Parliamentarians for Freedom of Religion or Belief (IPP FoRB) was launched last year in response to the rising crisis of religious or belief based persecution, both by terrorist groups and authoritarian governments.
"We've, all of us signed letters to three governments around the world where persecution is a real problem at the moment. One of them is Iran, another is Vietnam; and the third is Myanmar or Burma," said Labour MP Stephen Timms, representing the UK, speaking to Premier from New York.
Experience does suggest that letters like that signed by a wide range of parliamentarians from lots of different countries do have an effect on the governments that receive them," added Mr Timms.
In Iran only Armenians and Assyrians are allowed to be Christians, and even they are treated as second class citizens. Ethnic Persians are by definition Muslim, and any Muslim who leaves Islam is considered an 'apostate' and therefore 'unclean'. Churches are frequently monitored and raided by secret police; at least 75 Christians were arrested in 2014.
On Iran, Mr Timms did suggest some progress had been made at the conference in New York, due to the presence of an Iranian Ayatollah, representing the Academy of Sciences in Iran.
Mr Timms said: I think it rather a remarkable breakthrough to have someone like that at a conference like this and talking good sense about the importance of religious freedom."
Christians in Vietnam are viewed as Western agents, and their activities are closely monitored by the government; under Decree 92, which took effect in January 2013, all religious groups must be registered and abide by strict rules in the communist state.
Myanmar remains among the ten most violent states for Christians to live. Clashes on the Chinese border have taken place between the army and Christian-majority ethnic groups. In 2014 at least 20 Kachin Christians were killed and church buildings and homes destroyed. Though the government is still nominally Communist, Buddhism is the main instrument it uses to keep the nation united and under control.
Listen to Stephen Timms MP speaking to Premier's Des Busteed:
