AN independent Scotland would need to spend more than a £1 billion on international development to meet UN targets, according to a new report from 100 charities.

The report, Scotland's Place in Building a Just World, will be launched today and calls for a public debate about how the country should behave towards the rest of the world if it were to become independent - including calls for public contracts to go to ethical, tax-paying companies.

Backed by organisations such as Oxfam Scotland, SCIAF, Christian Aid and Concern Worldwide, the report supports the Swedish approach which ensures all government policies and legislations work to a "coherent" international development model.

It says any Scottish government must consider the global impact of all its policies and activities, not just those directly linked to international development.

It calls for a carbon tax on shipping emissions which would raise $25bn (£15.6bn) a year globally and could help fight climate change.

Chris Hegarty, senior policy and advocacy adviser for Christian Aid, said: "We are not taking a position on the referendum but this report considers the wider implications of international development.

"Scotland is an outward-looking country. Much of the constitutional debate around the referendum has been inward looking. It has been about looking down at the domestic situation and what might change here. But this is about challenging everyone to look up and consider what role Scotland could play in the world, either under devolution or independence."

Public sector procurement is worth £9bn a year in Scotland and the report makes clear that such money should "never exploit workers, harm the environment or reward unethical companies".

The report also says Scotland should spend at least 0.7% of its income on development and should enshrine this commitment in legislation. International Development is currently reserved to Westminster but the previous Scottish Executive set up international development funding which now equates to £9 million a year.

The report states: "It has long been acknowledged in Scotland that the policies of our devolved administration do not just affect people living in Scotland. Many of these policies have a profound impact on communities overseas, and for that reason we should not confine our international development reach to a single policy area, but to all policies that may and do impact internationally."

Philippa Bonella, SCIAF's head of education, said: "The debate on Scotland's constitutional future has provided an ideal opportunity for the international development sector to look at how Scottish Governments can combat the scandal of global poverty more effectively in the years ahead."