BEIJING (Reuters) - More than 20,000 people from Myanmar have flooded into border camps in neighboring China, seeking refuge from bitter fighting between ethnic groups and security forces in the country’s north, China said on Thursday.

Thousands of people have crossed China’s border in recent months to escape the conflict, which threatens Myanmar leader Aung San Suu Kyi’s top goal of reaching peace with minorities.

This week, about 30 people were killed in an attack by ethnic Chinese insurgents in Laukkai, a town 800 km (500 miles) northeast of Myanmar’s commercial hub Yangon.

China is providing humanitarian assistance while taking steps to ensure peace and tranquility in the border region, Foreign Ministry spokesman Geng Shuang said.

He reiterated a call for all sides involved to “exercise restraint and immediately cease fire” to keep clashes from escalating.

“China supports Myanmar’s peace process and hopes all sides can use peaceful means to resolve their differences via dialogue and consultation,” Geng told a regular news briefing.

Stray shells and bullets had fallen into China territory, injuring one Chinese person living there and causing some other damage, he added, but did not elaborate.

Suu Kyi’s nearly one-year-old government is increasingly besieged by ethnic rebels, grappling with an alliance of militias in Myanmar’s north and a new insurgency by Rohingyas rebelling against decades of persecution in the northwest.

Suu Kyi swept to power in 2015 on promises of national reconciliation and the meeting was aimed at giving fresh impetus to the stuttering peace process.

In this week’s attack, fighters of the predominantly ethnic Chinese Myanmar National Democratic Alliance Army (MNDAA) launched a pre-dawn raid on police, military and government sites in Laukkai, the capital of the northeastern Kokang region.

MNDAA is a part of the Northern Alliance coalition of rebel groups comprising one of Myanmar’s most powerful militias, the Kachin Independence Army (KIA), and two smaller groups caught in a stand-off with the military since 2015 clashes in the region.

Many died and tens of thousands fled during that fighting, which also spilled into China and led to the death of five of its people, angering Beijing.