Screen grab from a beheading in Saudi Arabia
Iran Sunday condemned Saudi Arabia's execution of 81men the previous day as a "violation of basic human rights principles and international law."
"This inhumane act was in violation of basic principles of human rights and international law, and contrary to human principles and accepted legal procedures," a ministry spokesperson said, according to state media.
Reports say that 41 of the victims were Shiite opponents of the government.
Iran itself has the highest number of executions in the world after China. In January alone it hanged 46 people. A number of high-profile political prisoners have also died in custody under suspicious circumstances.
Iran’s Shiite regime is a staunch enemy of Sunni Saudi Arabia and the two rivals have been engaged in bitter conflicts in the Middle East, including a seven-year war in Yemen.
On Sunday, Tehran also announced an end to talks with Riyadh, which started one year ago with Iraqi mediation to help solve their differences.
Saudi Arabia denies accusations of human rights abuses and says it protects its national security through its laws.
Its state news agency, SPA, said on Saturday the men executed on Saturday had the right to an attorney and were guaranteed their full rights under Saudi law during the judicial process.