STOCKHOLM, May 4 (Xinhua) -- Sweden's Social Democrat party has vowed to push for stricter migration rules in Sweden until the European Union (EU) introduces a common, EU-wide asylum policy, Prime Minister Stefan Lofven and migration minister Helene Fritzon said at a joint press conference on Friday.

Presenting his party's migration-policy platform ahead of Sweden's general election in September, Lofven said the share of asylum seekers taken in by Sweden must be proportional to the size of the country's population.

"It became particularly clear during the Fall of 2015 that the Swedish migration policy was not sustainable," Lofven told reporters.

"The fact that just a few EU countries took their share of responsibility during the refugee crisis was a major blowback and it showed, clearly, the importance of having a common system with functioning rules," he said.

At the press conference, Lofven and Fritzon said they plan to maintain the tightened asylum policy already in place in Sweden. It involves stricter rules for gaining permanent residency in Sweden.

Also, under the new proposals, undocumented migrant children will no longer have the right to attend school and rejected asylum seekers will lose the right to state benefits.

"Those who come here and get a positive response must integrate quickly into society and those who are rejected must leave the country," Lofven said.

Since the fall of 2015, the Social Democrat-Green Party coalition government has introduced a number of reforms to Sweden's migration policy.

The number of asylum seekers has since dropped from 160,000 in the record year of 2015 to around 27,000 last year. The prognosis for next year is 23,000. That is a move in the right direction, according to the Social Democrats, who now want to see an overall decrease in the number of people seeking asylum in Sweden.