By Michael Martina

WASHINGTON, July 14 (Reuters) - U.S. lawmakers on Tuesday introduced a bipartisan bill to increase penalties for foreign government agents who threaten people on U.S. soil, a move aimed at countering the rise of what officials call "transnational repression" by countries such as China and Iran.

The bill, put forward by Democratic Senator Adam Schiff and Republican Senator John Curtis, comes after China's ethnic unity law went into effect on July 1, establishing what Beijing says is its right to target certain critics beyond its borders.