China has exercised “great restraint” in the disputed South China Sea by not taking back islands occupied by other countries even though it could have, a senior Chinese diplomat said on Tuesday ahead of two regional summits.

China has overlapping claims with Vietnam, the Philippines, Malaysia, Taiwan and Brunei in the South China Sea, through which $5 trillion in ship-borne trade passes every year.

Chinese reclamation work and the building of airfields and other facilities on some of the islands it controls in the Spratly archipelago has alarmed the region and raised concern in Washington that China is extending its military reach deep into maritime Southeast Asia.

The issue is likely to feature in two summits this week, one in Manila and the other in Kuala Lumpur, both attended by US President Barack Obama.

Speaking in Beijing, Chinese vice foreign minister Liu Zhenmin said China did not want the South China Sea to be the focus of the East Asia summit in Kuala Lumpur later this week, which premier Li Keqiang will attend. But he noted it would be hard to avoid and that some countries would raise it.

While not on the formal agenda of the Asia-Pacific Economic Cooperation (Apec) summit on Wednesday and Thursday in Manila, the South China Sea is expected to be discussed on the sidelines.

China was the real victim in the South China Sea as it had had “dozens” of its islands and reefs in the Spratlys illegally occupied by three of the other claimants, Liu said.

He did not name the countries, but all claimants except Brunei have military fortifications in the Spratlys.

“The Chinese government has the right and the ability to recover the islands and reefs illegally occupied by neighbouring countries,” Liu said.

“But we haven’t done this. We have maintained great restraint with the aim to preserve peace and stability in the South China Sea.“

Liu said China’s island building was not about militarisation.

He also repeated Beijing’s standard line that while China’s building work is for defence, its main focus is civilian.

China is building facilities like lighthouses, while protecting the environment, Liu added.

He said the focus of the East Asia summit should be development.

“Hyping the South China Sea issue is not conducive to cooperation,” Liu said.

Disagreement between the United States and China over how to address rival claims in the South China Sea marred a gathering of regional defence ministers earlier this month, with a joint statement scrapped after officials failed to agree on its wording.

The United States had lobbied for inclusion of a reference to the waterway, while China had argued it had no place in the statement.