Outbound mergers and acquisitions by Chinese mainland companies in the current year are expected to be far less active, although a rebound in intensity of the deals may come in 2018, according to a report released by international accounting and financial services giant PricewaterhouseCoopers on Thursday.

Mainland companies announced 142 outbound M&As in the first quarter of this year, with a combined value of $21.2 billion. The volume and value of those deals dropped 39 percent and 77 percent, respectively, from record highs over the same period in 2016.

Chen Chao, director of PwC China transaction services, said there were two main reasons for the decrease.

"Since the fourth quarter of 2016, the regulatory authorities have pushed ahead with tougher requirements relating to authenticity and compliance of overseas investments by Chinese enterprises," Chen said.

"In the meantime, the global political and economic landscape has been undergoing a new round of rebalancing, with increasing external uncertainties."

The report said State-owned enterprises and private companies slowed down their pace of going abroad in the first quarter.

The report also said listed companies had been the main force of having outbound M&As because of their healthy funding and secure financing sources.

"After the blistering growth in 2016, there will be an obvious decrease in overseas acquisition deals this year and the recovery will come in 2018," said Wang Peng, PwC China tax partner.

The report showed that Europe and the United States are still they key destinations for overseas M&As by Chinese mainland companies.

In 2016 and the first quarter of 2017, nearly 60 percent of deals secured by mainland companies were in the European and US markets, according to the report.

In the first quarter of 2017, 32 percent of the total overseas M&As occurred in Asia, boosted by the Belt and Road Initiative.

"Cross-border M&As with strategic significance, especially industrial upgrading and the Belt and Road-related projects, will dominate the overseas M&A market in 2017," said Chen.