(CNN) -- President Barack Obama called modern day slavery "barbaric" and "evil" as he spoke out Tuesday against trafficking and praised companies, organizations and individuals fighting the traffickers.

He also signed an executive order strengthening protections against human trafficking for domestic federal contracts, and tightening anti-trafficking rules for government contracts abroad worth more than $500,000.

Speaking at the Clinton Global Initiative, Obama said: "It ought to concern every person, because it's a debasement of our common humanity. It ought to concern every community, because it tears at the social fabric.

"It ought to concern every business, because it distorts markets. It ought to concern every nation, because it endangers public health and fuels violence and organized crime.

"I'm talking about the injustice, the outrage, of human trafficking, which must be called by its true name -- modern slavery."

Obama praised businesses taking steps to fight trafficking in their industry, church groups for using their faith to tackle slavery and individuals trying to make sure the products they buy are slave-free.

He said: "Our fight against human trafficking is one of the great human rights causes of our time, and the United States will continue to lead it."

Obama also spoke about modern-day slavery in the U.S., from child sex slaves to migrant workers who have their documents taken from them.

He said: "Last year we charged a record number of predators with human trafficking... We are going to do more to spot it and stop it."

Obama said that would include working with train and bus employees and teachers to help identify potential trafficking victims.

He added: "Everyone has a responsibility. Every nation can take action."

The Obama executive order says contractors and subcontractors working in the U.S. on federal projects cannot use misleading recruitment practices; charge employees recruitment fees; and destroy or confiscate an employee's identity documents.

All those techniques are often used by traffickers as a way of luring in victims vulnerable to trafficking.

Internationally, the order says contractors and subcontractors on jobs worth more than $500,000 must have a trafficking awareness program, and a safe way to report trafficking suspicions. The contractors must also guarantee both they and workers or companies they hire are not involved in trafficking-related activities.

A White House news release read: "More than 20 million men, women, and children worldwide are victims of human trafficking.

"Companies around the world are taking steps to eliminate the potential for trafficked labor in their operations and supply chains, and President Obama is committed to protecting vulnerable individuals as government contractors and subcontractors perform vital services and manufacture goods procured by the United States.

"As the largest single purchaser of goods and services in the world, the U.S. Government has a responsibility to combat human trafficking at home and abroad, and to ensure American tax dollars do not contribute to this affront to human dignity."