A crowdfunding appeal that was launched after Russian attacks on cities across the country on Monday has raised $9.6m (£8.7m) in 24 hours for the purchase of kamikaze drones for the Ukrainian armed forces.

An initial 50 Ram II drones, unmanned aerial vehicles with a 3kg explosive payload, designed and built by Ukrainian companies, will be bought with the money, along with three control stations.

Further munitions would be secured over the coming days, said Serhiy Prytula, who organised the initiative.

He said: “They wanted to scare us but we united even more. Remember: never infuriate Ukrainians. Never. The people have donated for the revenge, so we will ensure the revenge happens.”

Ukraine’s president, Volodymyr Zelenskiy, told G7 leaders on Tuesday via video conference that Russia had used a variety of munitions to strike Ukrainian cities over the previous two days, killing 20 people.

“The enemy has used more than 100 cruise missiles, dozens of different drones, including Iranian Shaheds,” he said. “And every 10 minutes I receive a message about the enemy’s use of Iranian Shaheds.”

Zelenskiy added that Ukrainian intelligence believed Russia had ordered 2,400 Shahed-136 kamikaze drones from Iran, as he called on the west to provide Ukraine with better air-defence systems.

Shahed-136 drones, which like the Ram II are not designed to return from a trip, are made by the Iranian Aircraft Industrial Company and are said by their manufacturers to have a flight range of 1,000km. They are slow and contain a noisy Chinese MD550 engine but can be difficult to shoot down when sent in a swarm.

The Ram ІІ UAV has a flight range of 30km but has proven to be effective in combat, with footage shared on social media of one destroying a Russian 9K33 Osa surface-to-air missile system said to be worth £634,000.

Serhii Sternenko, an activist who co-founded the crowdfunding exercise, which was closed after 26 hours, said 1m UAH (£24,507) had been donated in the first seven minutes of the appeal from people in bomb shelters and elsewhere.

He said: “Crowdfunding campaigns make our defence stronger; we, the people, help the Ukrainian army. But we still need more weapons from our allies to stop this terror and the crime of genocide Russia commits daily in this European country.”