Dmitry Medvedev, Russian prime minister, submitted his resignation to President Vladimir Putin on Wednesday, Russia's Tass news agency reported.

Russian media said Putin thanked Medvedev for his work. They said that Putin will name Medvedev as deputy secretary of the presidential Security Council.

Putin asked Medvedev's Cabinet ministers to keep working until a new one is formed, Russian media said.

Medvedev has served as Russia's prime minister since 2012. He spent four years before that as president from 2008.

Medvedev's resignation followed Putin's annual state of the nation address earlier on Wednesday.

During Putin's address to the Federal Assembly in Moscow, he proposed a national referendum on amendments to the Russian Constitution.

According to Putin, Russians may be asked to vote on some key changes to the Constitution, including setting out its supremacy over international law, as well as tightening background requirements for presidential candidates.

The amendments to the Constitution could be brought up for a popular vote to ensure "the development of Russia as a "welfare and rule-of-law state", he said.

Putin suggested stricter profiling of top officials, starting with the presidential candidates and going all the way down.

An amended Constitution would include requirements for "persons holding positions crucial for ensuring the country's security and sovereignty", like the prime minister, Cabinet ministers, governors, and heads of federal agencies, and that they should be barred from having foreign citizenships or residence permits.

In his address, Putin also called on nuclear-armed countries to work on a common approach aimed at preventing a global war.

He said the five permanent United Nations Security Council members－Russia, the United States, China, the United Kingdom and France－must devise "measures aimed at neutralizing any conditions for a global war".

Putin also said, for the first time in history, Russia is "not catching up" to anyone in terms of its military . Instead, he said, it is the other countries that are racing to develop advanced weapons that Russia already possessed.

During Putin's 15th state of the nation address since 2000, he called on the government to resolve large-scale social, economic problems "without delay".

The speech, which was different from previous addresses when Putin addressed many international issues and military developments, also saw the president focus a lot on domestic issues.

For one thing, he said he was dissatisfied with Russia's birthrate, saying low incomes of most households with children directly threatened Russia's demographic future.

"There are almost 147 million people in Russia today, but the country has entered a tense demographic period, with birthrates falling again," Putin said.

Agencies contributed to this story.