BERLIN (REUTERS) - German Chancellor Angela Merkel told Russian President Vladimir Putin more Organisation for Security and Cooperation in Europe (OSCE) observers should be sent to Ukraine, a plan he welcomed, Ms Merkel's spokesman said on Sunday.

"The chancellor proposed swiftly expanding the existing OSCE presence in Ukraine and sending a bigger number of observers into hot spots, especially in East Ukraine," Ms Merkel's spokesman Steffen Seibert said in a statement about a phone call between the two leaders.

"The Russian president viewed this initiative positively. He promised he would instruct Foreign Minister (Sergei) Lavrov accordingly." This should be agreed with as broad as possible support at an OSCE meeting in Vienna on Monday.

Their phone conversation came as Ukraine's Prime Minister Arseniy Yatsenyuk called Sunday for foreign observers from the OSCE to be urgently sent to the east and south of the country as Crimea threatened to secede and join Russia, reported AFP.

"Their mandate should include the east and south of Ukraine, including Crimea," Yatsenyuk said in a statement, adding that he hoped for a quick decision by OSCE.

Ms Merkel also condemned a Russian attempt on Saturday to try to enter a spit of land belonging to Kherson, a region adjacent to Crimea, Seibert said in the statement.