ADEN, Yemen, Dec. 27 (Xinhua) -- United Nations Special Envoy for Yemen Hans Grundberg on Saturday called on all parties to exercise restraint and avoid further escalation, as tensions mount in Yemen's eastern governorates of Hadramout and Al-Mahrah.

In a statement posted on social media platform X, Grundberg reiterated the UN secretary-general's call for "restraint, de-escalation and dialogue," urging all parties to avoid actions that could further complicate the situation.

He underscored the importance of ongoing regional mediation efforts, noting that he remains engaged with Yemeni and regional stakeholders in support of de-escalation and progress toward "a comprehensive and inclusive political solution" to the conflict in Yemen.

Grundberg made the remarks after Saudi Arabia carried out airstrikes on Friday targeting Southern Transitional Council (STC) sites, including positions of the Hadrami Elite Forces in the Ghayl bin Yamin area near key oil fields. No casualties or damage to military equipment were reported.

The strikes followed the STC's latest military expansion in eastern Yemen. On Dec. 3, STC forces took control of Hadramout after clashes with pro-government units, before extending their presence into the eastern province of Al-Mahrah without reported resistance. The group has since recruited local forces in both provinces, despite repeated calls from the Yemeni government and Saudi Arabia for de-escalation.

Earlier in the day, Turki Al Maliki, spokesperson for the Saudi-led coalition in Yemen, said that any military movements undermining de-escalation efforts would be addressed to protect civilians, the Saudi Press Agency reported.

Yemen's Presidential Leadership Council (PLC) Chairman Rashad Al-Alimi on Saturday welcomed the coalition's measures to curb what he described as destabilizing actions by the STC in the two governorates.

Formed in 2017, the STC seeks self-determination and eventual independence for southern Yemen. Although it joined the Saudi-led coalition and was integrated into Yemen's internationally recognized government in 2022, the group continues to press for southern secession. The STC has accused previous Yemeni governments of politically and economically marginalizing the south, a claim Yemeni authorities deny. ■