Participants at the UK Ministerial on Freedom of Religion or Belief have heard calls to end the criminalisation of apostasy and blasphemy.
Lord Alton, addressing a fringe event, decried the "harsh and extra-legal punishments" that exist in some countries for apostasy and blasphemy.
Afghanistan, Pakistan and Iran were some of the countries singled out for criticism during the event.
"The UN Secretary General, in his annual report on the question of the death penalty, made clear that the death penalty 'must never be imposed as a sanction for specific forms of nonviolent conduct such as apostasy, blasphemy, adultery, and consensual same-sex relations'.
"Despite this, at least 12 nations continue to maintain the death penalty for apostasy and blasphemy," Lord Alton said.
He drew attention to the recent "horrific" murder of Christian student Deborah Samuel Yakubu, who was stoned to death in Nigeria and her body set on fire by her classmates after being accused of blasphemy.
Concern was also voiced about Christian converts and Ahmadiyya Muslim minorities currently on death row for alleged blasphemy in Pakistan.
The fringe event was held jointly by the Jubilee Campaign in collaboration with Set My People Free and Humanists UK.
Lord Alton said that while some places had seen "remarkable progress" in repealing blasphemy and apostasy laws in recent years, "more must be done to bring about a global end to the use of capital punishment for perceived religious offenses".
The Jubilee Campaign and Set My People Free are calling for United Nations General Assembly resolutions on executions and the death penalty this year to declare that "the death penalty can never be imposed as a sanction for non-violent conduct such as apostasy and blasphemy".